A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of
vascular plant
Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They ...
s (plants with
xylem
Xylem is one of the two types of transport tissue in vascular plants, the other being phloem. The basic function of xylem is to transport water from roots to stems and leaves, but it also transports nutrients. The word ''xylem'' is derived from ...
and
phloem
Phloem (, ) is the living tissue in vascular plants that transports the soluble organic compounds made during photosynthesis and known as ''photosynthates'', in particular the sugar sucrose, to the rest of the plant. This transport process is c ...
) that reproduce via
spore
In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, ...
s and have neither
seed
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosper ...
s nor
flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechanis ...
s. The
polypodiophytes include all living
pteridophyte
A pteridophyte is a vascular plant (with xylem and phloem) that disperses spores. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as " cryptogams", meaning that their means of reproduction is hidden. Fer ...
s except the
lycopods
Lycopodiopsida is a class of vascular plants known as lycopods, lycophytes or other terms including the component lyco-. Members of the class are also called clubmosses, firmosses, spikemosses and quillworts. They have dichotomously branching s ...
, and differ from
moss
Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta ('' sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and ...
es and other
bryophyte
The Bryophyta s.l. are a proposed taxonomic division containing three groups of non-vascular land plants (embryophytes): the liverworts, hornworts and mosses. Bryophyta s.s. consists of the mosses only. They are characteristically limited in s ...
s by being vascular, i.e., having specialized tissues that conduct water and nutrients and in having life cycles in which the branched
sporophyte
A sporophyte () is the diploid multicellular stage in the life cycle of a plant or alga which produces asexual spores. This stage alternates with a multicellular haploid gametophyte phase.
Life cycle
The sporophyte develops from the zygote ...
is the dominant phase.
Ferns have complex
leaves
A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, st ...
called
megaphylls, that are more complex than the
microphyll
In plant anatomy and evolution a microphyll (or lycophyll) is a type of plant leaf with one single, unbranched leaf vein. Plants with microphyll leaves occur early in the fossil record, and few such plants exist today. In the classical concept of ...
s of
clubmosses
Lycopodiopsida is a class of vascular plants known as lycopods, lycophytes or other terms including the component lyco-. Members of the class are also called clubmosses, firmosses, spikemosses and quillworts. They have dichotomously branching ...
. Most ferns are
leptosporangiate fern
The Polypodiidae, commonly called leptosporangiate ferns, formerly Leptosporangiatae, are one of four subclasses of ferns, and the largest of these, being the largest group of living ferns, including some 11,000 species worldwide. The group has ...
s. They produce coiled
fiddleheads that uncoil and expand into
frond
A frond is a large, divided leaf. In both common usage and botanical nomenclature, the leaves of ferns are referred to as fronds and some botanists restrict the term to this group. Other botanists allow the term frond to also apply to the lar ...
s. The group includes about 10,560 known extant species. Ferns are defined here in the broad sense, being all of the
Polypodiopsida
A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes exce ...
, comprising both the leptosporangiate (
Polypodiidae) and
eusporangiate fern
Eusporangiate ferns are vascular spore plants, whose sporangia arise from several epidermal cells and not from a single cell as in leptosporangiate ferns. Typically these ferns have reduced root systems and sporangia that produce large amounts o ...
s, the latter group including
horsetail
''Equisetum'' (; horsetail, snake grass, puzzlegrass) is the only living genus in Equisetaceae, a family of ferns, which reproduce by spores rather than seeds.
''Equisetum'' is a "living fossil", the only living genus of the entire subclass ...
s,
whisk ferns,
marattioid fern
Marattiaceae is the only family of extant (living) ferns in the order Marattiales. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), Marattiales is the only order in the subclass Marattiidae. The family has six genera and about ...
s, and
ophioglossoid ferns.
Ferns first appear in the fossil record about 360 million years ago in the late
Devonian
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, wh ...
period, but many of the current families and species did not appear until roughly 145 million years ago in the early
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
, after flowering plants came to dominate many environments. The fern ''
Osmunda claytoniana
''Claytosmunda'' is a genus of fern. It has only one extant species, ''Claytosmunda claytoniana'' ( synonym ''Osmunda claytoniana''), the interrupted fern, native to Eastern Asia, Eastern United States, and Eastern Canada.
The specific epith ...
'' is a paramount example of
evolutionary stasis; paleontological evidence indicates it has remained unchanged, even at the level of fossilized nuclei and chromosomes, for at least 180 million years.
Ferns are not of major economic importance, but some are used for food, medicine, as
biofertilizer, as ornamental plants, and for remediating contaminated soil. They have been the subject of research for their ability to remove some chemical pollutants from the atmosphere. Some fern species, such as
bracken
Bracken (''Pteridium'') is a genus of large, coarse ferns in the family (biology), family Dennstaedtiaceae. Ferns (Pteridophyta) are vascular plants that have alternating generations, large plants that produce spores and small plants that produ ...
(''Pteridium aquilinum'') and water fern (''
Azolla filiculoides
''Azolla filiculoides'' (water fern) is a species of ''Azolla'', native to warm temperate and tropical regions of the Americas which was introduced to Europe, North and sub-Saharan Africa, China, Japan, New Zealand, Australia, the Caribbean and H ...
'') are significant weeds worldwide. Some fern genera, such as ''
Azolla
''Azolla'' (mosquito fern, duckweed fern, fairy moss, water fern) is a genus of seven species of aquatic ferns in the family Salviniaceae. They are extremely reduced in form and specialized, looking nothing like other typical ferns but more rese ...
'', can
fix nitrogen and make a significant input to the nitrogen nutrition of
rice paddies. They also play certain roles in folklore.
Description
Extant ferns are herbaceous
perennials
A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also widel ...
and most lack
wood
Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin ...
y growth. Their foliage may be
deciduous
In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, ...
or
evergreen
In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, whic ...
, and some are semi-evergreen depending on the climate. Like the sporophytes of seed plants, those of ferns consist of stems, leaves and roots. Ferns differ from seed plants in reproducing by spores. However, they also differ from spore-producing
bryophyte
The Bryophyta s.l. are a proposed taxonomic division containing three groups of non-vascular land plants (embryophytes): the liverworts, hornworts and mosses. Bryophyta s.s. consists of the mosses only. They are characteristically limited in s ...
s in that, like seed plants, they are
polysporangiophytes, their sporophytes branching and producing many sporangia. Also unlike bryophytes, fern sporophytes are free-living and only briefly dependent on the maternal
gametophyte
A gametophyte () is one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the ...
.
Stems
Fern stems are often referred to as
rhizome
In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow ...
s, even though they grow underground only in some of the species. Epiphytic species and many of the terrestrial ones have above-ground creeping
stolon
In biology, stolons (from Latin '' stolō'', genitive ''stolōnis'' – "branch"), also known as runners, are horizontal connections between organisms. They may be part of the organism, or of its skeleton; typically, animal stolons are external s ...
s (e.g.,
Polypodiaceae
Polypodiaceae is a family of ferns. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), the family includes around 65 genera and an estimated 1,650 species and is placed in the order Polypodiales, suborder Polypodiineae. A broade ...
), and many groups have above-ground erect semi-woody trunks (e.g.,
Cyatheaceae
The Cyatheaceae are a family of ferns, the scaly tree ferns, one of eight families in the order Cyatheales in the Pteridophyte Phylogeny Group classification of 2016 (PPG I). Alternatively, the family may defined much more broadly (Cyatheaceae '' ...
). These can reach up to tall in a few species (e.g., ''
Cyathea brownii'' on
Norfolk Island
Norfolk Island (, ; Norfuk: ''Norf'k Ailen'') is an external territory of Australia located in the Pacific Ocean between New Zealand and New Caledonia, directly east of Australia's Evans Head and about from Lord Howe Island. Together wit ...
and ''
Cyathea medullaris
''Sphaeropteris medullaris'', synonym ''Cyathea medullaris'', commonly known as mamaku or black tree fern, is a large tree fern up to 20 m tall. It is distributed across the south-west Pacific from Fiji to Pitcairn Island. Its other Māori name ...
'' in
New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island coun ...
).
Leaves
The
green
Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a combin ...
,
photosynthetic
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in ...
part of the plant is technically a
megaphyll and in ferns, it is often referred to as a ''
frond
A frond is a large, divided leaf. In both common usage and botanical nomenclature, the leaves of ferns are referred to as fronds and some botanists restrict the term to this group. Other botanists allow the term frond to also apply to the lar ...
''. New leaves typically expand by the unrolling of a tight spiral called a crozier or
fiddlehead
Fiddleheads or fiddlehead greens are the furled fronds of a young fern, harvested for use as a vegetable.
Left on the plant, each fiddlehead would unroll into a new frond (circinate vernation). As fiddleheads are harvested early in the sea ...
into
frond
A frond is a large, divided leaf. In both common usage and botanical nomenclature, the leaves of ferns are referred to as fronds and some botanists restrict the term to this group. Other botanists allow the term frond to also apply to the lar ...
s. This uncurling of the leaf is termed
circinate vernation. Leaves are divided into two types: sporophylls and tropophylls.
Sporophylls produce spores;
tropophylls do not. Fern spores are borne in
sporangia
A sporangium (; from Late Latin, ) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other lineages form sporangia at some point in their life cy ...
which are usually clustered to form
sori. In monomorphic ferns, the fertile and sterile leaves looks morphologically the same, and are photosynthesizing in the same way. In hemidimorphic ferns, just a portion of the fertile leaf is different from the sterile leaves. And in dimorphic ferns, also called holomorphic ferns, the two types of leaves are morphologically distinct (
frond dimorphism
Frond dimorphism refers to a difference in ferns between the fertile and sterile fronds. Since ferns, unlike flowering plants, bear spores on the leaf blade itself, this may affect the form of the frond itself. In some species of ferns, there i ...
). The fertile leaves are much narrower than the sterile leaves, and may even have no green tissue at all (e.g.,
Blechnaceae
Blechnaceae is a family of ferns in the order Polypodiales, with a cosmopolitan distribution. Its status as a family and the number of genera included have both varied considerably. In the Pteridophyte Phylogeny Group classification of 201 ...
,
Lomariopsidaceae). The anatomy of fern leaves can be anywhere from simple to highly divided, or even
indeterminate (e.g.
Gleicheniaceae,
Lygodiaceae
''Lygodium'' (climbing fern) is a genus of about 40 species of ferns, native to tropical regions across the world, with a few temperate species in eastern Asia and eastern North America. It is the sole genus in the family Lygodiaceae in the Pter ...
). The divided forms are
pinnate
Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, an ...
, where the leaf segments are completely separated from one other, or pinnatifid (partially pinnate), where the leaf segments are still partially connected. When the fronds are branched more than once, it can also be a combination of the pinnatifid are pinnate shapes. If the leaf blades are divided twice, the plant has bipinnate fronds, and tripinnate fronds if they branch three times, and all the way to tetra- and pentapinnate fronds. In tree ferns, the main stalk that connects the leaf to the stem (known as the stipe), often has multiple leaflets. The leafy structures that grow from the stipe are known as pinnae and are often again divided into smaller pinnules.
Roots
The underground non-photosynthetic structures that take up water and nutrients from
soil
Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former ...
. They are always
fibrous
Fiber or fibre (from la, fibra, links=no) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorporat ...
and structurally are very similar to the roots of seed plants.
As in all other
vascular plants
Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They ...
, the
sporophyte
A sporophyte () is the diploid multicellular stage in the life cycle of a plant or alga which produces asexual spores. This stage alternates with a multicellular haploid gametophyte phase.
Life cycle
The sporophyte develops from the zygote ...
is the dominant phase or generation in the life cycle. The
gametophytes of ferns, however, are very different from those of seed plants. They are free-living and resemble
liverworts
The Marchantiophyta () are a division of non-vascular land plants commonly referred to as hepatics or liverworts. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of ...
, whereas those of seed plants develop within the spore wall and are dependent on the parent sporophyte for their nutrition. A fern gametophyte typically consists of:
*
Prothallus: A green, photosynthetic structure that is one cell thick, usually heart or kidney shaped, 3–10 mm long and 2–8 mm broad. The prothallus produces gametes by means of:
**
Antheridia: Small spherical structures that produce
flagellate
A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word ''flagellate'' also describes a particular construction (or level of organization) characteristic of many prokaryotes and eukaryotes and thei ...
sperm.
**
Archegonia
An archegonium (pl: archegonia), from the ancient Greek ''ἀρχή'' ("beginning") and ''γόνος'' ("offspring"), is a multicellular structure or organ of the gametophyte phase of certain plants, producing and containing the ovum or female ga ...
: A flask-shaped structure that produces a single egg at the bottom, reached by the sperm by swimming down the neck.
*
Rhizoids:
root
In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the su ...
-like structures (not true roots) that consist of single greatly elongated cells, that absorb water and mineral
salts
In chemistry, a salt is a chemical compound consisting of an ionic assembly of positively charged cations and negatively charged anions, which results in a compound with no net electric charge. A common example is table salt, with positively c ...
over the whole structure. Rhizoids anchor the prothallus to the soil.
Taxonomy
Carl Linnaeus
Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, ...
(1753) originally recognized 15 genera of ferns and fern allies, classifying them in class
Cryptogamia in two groups, Filices (e.g. ''
Polypodium'') and
Musci (mosses). By 1806 this had increased to 38 genera, and has progressively increased since (''see Figure 1''). Ferns were traditionally classified in the
class
Class or The Class may refer to:
Common uses not otherwise categorized
* Class (biology), a taxonomic rank
* Class (knowledge representation), a collection of individuals or objects
* Class (philosophy), an analytical concept used differently ...
Filices, and later in a
Division of the Plant Kingdom named
Pteridophyta
A pteridophyte is a vascular plant (with xylem and phloem) that disperses spores. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as " cryptogams", meaning that their means of reproduction is hidden. Ferns ...
or Filicophyta. Pteridophyta is no longer recognised as a valid
taxon
In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular n ...
because it is
paraphyletic
In taxonomy, a group is paraphyletic if it consists of the group's last common ancestor and most of its descendants, excluding a few monophyletic subgroups. The group is said to be paraphyletic ''with respect to'' the excluded subgroups. In ...
. The ferns are also referred to as Polypodiophyta or, when treated as a subdivision of
Tracheophyta (vascular plants), Polypodiopsida, although this name sometimes only refers to leptosporangiate ferns. Traditionally, all of the spore producing
vascular plant
Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They ...
s were informally denominated the
pteridophyte
A pteridophyte is a vascular plant (with xylem and phloem) that disperses spores. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as " cryptogams", meaning that their means of reproduction is hidden. Fer ...
s, rendering the term synonymous with ferns and
fern allies. This can be confusing because members of the division Pteridophyta were also denominated pteridophytes (''sensu stricto'').
Traditionally, three discrete groups have been denominated ferns: two groups of eusporangiate ferns, the families
Ophioglossaceae
Ophioglossaceae, the adder's-tongue family, is a small family of ferns. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), it is the only family in the order Ophioglossales, which together with the Psilotales is placed in the s ...
(
adder's tongues,
moonwort
''Botrychium'' is a genus of ferns, seedless vascular plants in the family Ophioglossaceae. ''Botrychium'' species are known as moonworts. They are small, with fleshy roots, and reproduce by spores shed into the air. One part of the leaf, the ...
s, and grape ferns) and
Marattiaceae
Marattiaceae is the only family of extant (living) ferns in the order Marattiales. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), Marattiales is the only order in the subclass Marattiidae. The family has six genera and about ...
; and the leptosporangiate ferns. The Marattiaceae are a primitive group of tropical ferns with large, fleshy rhizomes and are now thought to be a
sibling taxon to the leptosporangiate ferns. Several other groups of species were considered fern allies: the
clubmoss
Lycopodiopsida is a class of vascular plants known as lycopods, lycophytes or other terms including the component lyco-. Members of the class are also called clubmosses, firmosses, spikemosses and quillworts. They have dichotomously branching ...
es,
spikemoss
''Selaginella'' is the sole genus of vascular plants in the family Selaginellaceae, the spikemosses or lesser clubmosses.
This family is distinguished from Lycopodiaceae (the clubmosses) by having scale-leaves bearing a ligule and by having ...
es, and
quillworts in
Lycopodiophyta; the whisk ferns of
Psilotaceae
Psilotaceae is a family of ferns (class Polypodiopsida) consisting of two genera, ''Psilotum'' and '' Tmesipteris'' with about a dozen species. It is the only family in the order Psilotales.
Description
Once thought to be descendants of early v ...
; and the horsetails of
Equisetaceae. Since this grouping is
polyphyletic
A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of conver ...
, the term fern allies should be abandoned, except in a historical context. More recent genetic studies demonstrated that the Lycopodiophyta are more distantly related to other
vascular plant
Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They ...
s, having radiated evolutionarily at the base of the vascular plant
clade
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English ter ...
, while both the whisk ferns and horsetails are as closely related to leptosporangiate ferns as the
ophioglossoid ferns and
Marattiaceae
Marattiaceae is the only family of extant (living) ferns in the order Marattiales. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), Marattiales is the only order in the subclass Marattiidae. The family has six genera and about ...
. In fact, the whisk ferns and ophioglossoid ferns are demonstrably a
clade
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English ter ...
, and the
horsetail
''Equisetum'' (; horsetail, snake grass, puzzlegrass) is the only living genus in Equisetaceae, a family of ferns, which reproduce by spores rather than seeds.
''Equisetum'' is a "living fossil", the only living genus of the entire subclass ...
s and
Marattiaceae
Marattiaceae is the only family of extant (living) ferns in the order Marattiales. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), Marattiales is the only order in the subclass Marattiidae. The family has six genera and about ...
are arguably another clade.
Molecular phylogenetics
Smith et al. (2006) carried out the first higher-level pteridophyte classification published in the
molecular phylogenetic
Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...
era, and considered the ferns as monilophytes, as follows:
*
Division Tracheophyta (tracheophytes) - vascular plants
**
Sub division Euphyllophytina
The euphyllophytes are a clade of plants within the tracheophytes (the vascular plants). The group may be treated as an unranked clade, a division under the name Euphyllophyta or a subdivision under the name Euphyllophytina. The euphyllophytes a ...
(euphyllophytes)
*** Infradivision
Moniliformopses
A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes exce ...
(monilophytes)
*** Infradivision
Spermatophyta
A spermatophyte (; ), also known as phanerogam (taxon Phanerogamae) or phaenogam (taxon Phaenogamae), is any plant that produces seeds, hence the alternative name seed plant. Spermatophytes are a subset of the embryophytes or land plants. They inc ...
- seed plants, ~260,000 species
** Subdivision
Lycopodiophyta (lycophytes) - less than 1% of extant vascular plants
Molecular data, which remain poorly constrained for many parts of the plants' phylogeny, have been supplemented by morphological observations supporting the inclusion of Equisetaceae in the ferns, notably relating to the construction of their sperm and peculiarities of their roots. However, there remained differences of opinion about the placement of the genus ''
Equisetum
''Equisetum'' (; horsetail, snake grass, puzzlegrass) is the only living genus in Equisetaceae, a family of ferns, which reproduce by spores rather than seeds.
''Equisetum'' is a "living fossil", the only living genus of the entire subclass ...
'' (see
Equisetopsida for further discussion). One possible solution was to denominate only the leptosporangiate ferns as "true ferns" while denominating the other three groups as fern allies. In practice, numerous classification schemes have been proposed for ferns and fern allies, and there has been little consensus among them.
The leptosporangiate ferns are sometimes called "true ferns". This group includes most plants familiarly known as ferns. Modern research supports older ideas based on morphology that the Osmundaceae diverged early in the evolutionary history of the leptosporangiate ferns; in certain ways this family is intermediate between the eusporangiate ferns and the leptosporangiate ferns. Rai and Graham (2010) broadly supported the primary groups, but queried their relationships, concluding that "at present perhaps the best that can be said about all relationships among the major lineages of monilophytes in current studies is that we do not understand them very well".
[, p. 1450] Grewe et al. (2013) confirmed the inclusion of horsetails within ferns ''sensu lato'', but also suggested that uncertainties remained in their precise placement.
[ Other classifications have raised Ophioglossales to the rank of a fifth class, separating the whisk ferns and ophioglossoid ferns.][
One problem with the classification of ferns is that of ]cryptic species
In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each ot ...
. A cryptic species is a species that is morphologically similar to another species, but differs genetically in ways that prevent fertile interbreeding. A good example of this is the currently designated species ''Asplenium trichomanes
''Asplenium trichomanes'', the maidenhair spleenwort, is a small fern in the spleenwort genus ''Asplenium''. It is a widespread and common species, occurring almost worldwide in a variety of rocky habitats. It is a variable fern with several subs ...
'' (maidenhair spleenwort). This is actually a species complex that includes distinct diploid and tetraploid races. There are minor but unclear morphological differences between the two groups, which prefer distinctly differing habitats. In many cases such as this, the species complexes have been separated into separate species, thus raising the total number of species of ferns. Many more cryptic species may be yet to be discovered and designated.
Phylogeny
The ferns are related to other higher order taxa as shown in the following cladogram:
Nomenclature and subdivision
The classification of Smith et al. (2006) treated ferns as four classes:
* Equisetopsida (Sphenopsida) 1 order, Equisetales
Equisetales is an order of subclass Equisetidae with only one living family, Equisetaceae, containing the genus '' Equisetum'' (horsetails).
Classification
In the molecular phylogenetic classification of Smith et al. in 2006, Equisetales, in i ...
(Horsetail
''Equisetum'' (; horsetail, snake grass, puzzlegrass) is the only living genus in Equisetaceae, a family of ferns, which reproduce by spores rather than seeds.
''Equisetum'' is a "living fossil", the only living genus of the entire subclass ...
s) ~ 15 species
* Psilotopsida 2 orders ( whisk ferns and ophioglossoid ferns) ~92 species
* Marattiopsida
Marattiaceae is the only family of extant (living) ferns in the order Marattiales. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), Marattiales is the only order in the subclass Marattiidae. The family has six genera and abou ...
1 order, Marattiales
Marattiaceae is the only family of extant (living) ferns in the order Marattiales. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), Marattiales is the only order in the subclass Marattiidae. The family has six genera and abou ...
~ 150 species
* Polypodiopsida
A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes exce ...
(Filicopsida) 7 orders (leptosporangiate fern
The Polypodiidae, commonly called leptosporangiate ferns, formerly Leptosporangiatae, are one of four subclasses of ferns, and the largest of these, being the largest group of living ferns, including some 11,000 species worldwide. The group has ...
s) ~ 9,000 species
In addition they defined 11 orders and 37 families. That system was a consensus of a number of studies, and was further refined. The phylogenetic relationships are shown in the following cladogram
A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...
(to the level of orders).[ This division into four major clades was then confirmed using morphology alone.
Subsequently, ]Chase
Chase or CHASE may refer to:
Businesses
* Chase Bank, a national bank based in New York City, New York
* Chase Aircraft (1943–1954), a defunct American aircraft manufacturing company
* Chase Coaches, a defunct bus operator in England
* Chase C ...
and Reveal considered both lycopods and ferns as subclasses of a class Equisetopsida (Embryophyta
The Embryophyta (), or land plants, are the most familiar group of green plants that comprise vegetation on Earth. Embryophytes () have a common ancestor with green algae, having emerged within the Phragmoplastophyta clade of green algae as siste ...
) encompassing all land plants. This is referred to as Equisetopsida ''sensu lato
''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular c ...
'' to distinguish it from the narrower use to refer to horsetails alone, Equisetopsida ''sensu stricto''. They placed the lycopods into subclass Lycopodiidae and the ferns, keeping the term monilophytes, into five subclasses, Equisetidae, Ophioglossidae, Psilotidae, Marattiidae and Polypodiidae, by dividing Smith's Psilotopsida into its two orders and elevating them to subclass (Ophioglossidae and Psilotidae). Christenhusz et al. (2011) followed this use of subclasses but recombined Smith's Psilotopsida as Ophioglossidae, giving four subclasses of ferns again.
Christenhusz
Dr Maarten Joost Maria Christenhusz (born 27 April 1976) is a Dutch botanist, natural historian and photographer.
Career
He was born in Enschede, the Netherlands, received his undergraduate and master's degrees from Utrecht University in Bi ...
and Chase
Chase or CHASE may refer to:
Businesses
* Chase Bank, a national bank based in New York City, New York
* Chase Aircraft (1943–1954), a defunct American aircraft manufacturing company
* Chase Coaches, a defunct bus operator in England
* Chase C ...
(2014) developed a new classification of ferns and lycopods. They used the term Polypodiophyta for the ferns, subdivided like Smith et al. into four groups (shown with equivalents in the Smith system), with 21 families, approximately 212 genera and 10,535 species;
* Equisetidae
Equisetidae is one of the four subclasses of Polypodiopsida (ferns), a group of vascular plants with a fossil record going back to the Devonian. They are commonly known as horsetails. They typically grow in wet areas, with whorls of needle-lik ...
(=Equisetopsida) - monotypic
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...
(Equisetales, Equisetaceae, ''Equisetum
''Equisetum'' (; horsetail, snake grass, puzzlegrass) is the only living genus in Equisetaceae, a family of ferns, which reproduce by spores rather than seeds.
''Equisetum'' is a "living fossil", the only living genus of the entire subclass ...
'') horsetails ~ 20 species)
* Ophioglossidae
Ophioglossidae is one of the four subclasses of Polypodiopsida (ferns). This subclass consists of the ferns commonly known as whisk ferns, grape ferns, adder's-tongues and moonworts. It is equivalent to the class Psilotopsida in previous treatme ...
(=Psilotopsida) - 2 monotypic orders ~ 92 species
* Marattiidae
Marattiaceae is the only family of extant (living) ferns in the order Marattiales. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), Marattiales is the only order in the subclass Marattiidae. The family has six genera and about ...
(=Marattiopsida) - 1 monotypic order (Marattiales, Marattiaceae
Marattiaceae is the only family of extant (living) ferns in the order Marattiales. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), Marattiales is the only order in the subclass Marattiidae. The family has six genera and about ...
, 2 subfamilies) ~ 130 species
* Polypodiidae (=Polypodiopsida) - 7 orders
This was a considerable reduction in the number of families from the 37 in the system of Smith et al., since the approach was more that of lumping
Lumpers and splitters are opposing factions in any discipline that has to place individual examples into rigorously defined categories. The lumper–splitter problem occurs when there is the desire to create classifications and assign examples t ...
rather than splitting. For instance a number of families were reduced to subfamilies. Subsequently, a consensus group was formed, the Pteridophyte Phylogeny Group (PPG), analogous to the Angiosperm Phylogeny Group
The Angiosperm Phylogeny Group (APG) is an informal international group of systematic botanists who collaborate to establish a consensus on the taxonomy of flowering plants (angiosperms) that reflects new knowledge about plant relationships disc ...
, publishing their first complete classification in November 2016. They recognise ferns as a class, the Polypodiopsida, with four subclasses as described by Christenhusz and Chase, and which are phylogenetically related as in this cladogram:
In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), the Polypodiopsida consist of four subclasses, 11 orders, 48 families, 319 genera, and an estimated 10,578 species. Thus Polypodiopsida in the broad sense (''sensu lato'') as used by the PPG (Polypodiopsida ''sensu'' PPG I) needs to be distinguished from the narrower usage (''sensu stricto'') of Smith et al. (Polypodiopsida ''sensu'' Smith et al.) Classification of ferns remains unresolved and controversial with competing viewpoints (splitting vs lumping
Lumpers and splitters are opposing factions in any discipline that has to place individual examples into rigorously defined categories. The lumper–splitter problem occurs when there is the desire to create classifications and assign examples t ...
) between the systems of the PPG on the one hand and Christenhusz and Chase on the other, respectively. In 2018, Christenhusz and Chase explicitly argued against recognizing as many genera as PPG I.
Evolution and biogeography
Fern-like taxa (''Wattieza
''Wattieza'' was a genus of prehistoric trees that existed in the mid-Devonian that belong to the cladoxylopsids, close relatives of the modern ferns and horsetails. The 2005 (publicly revealed in 2007) discovery in Schoharie County, New York ...
'') first appear in the fossil record in the middle Devonian
The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, wh ...
period, ca. 390 Mya. By the Triassic
The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest per ...
, the first evidence of ferns related to several modern families appeared. The great fern radiation occurred in the late Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
, when many modern families of ferns first appeared. Ferns evolved to cope with low-light conditions present under the canopy of angiosperms.
Remarkably, the photoreceptor neochrome in the two orders Cyatheales and Polypodiales, integral to their adaptation to low-light conditions, was obtained via horizontal gene transfer
Horizontal gene transfer (HGT) or lateral gene transfer (LGT) is the movement of genetic material between unicellular and/or multicellular organisms other than by the ("vertical") transmission of DNA from parent to offspring (reproduction). H ...
from hornworts, a bryophyte
The Bryophyta s.l. are a proposed taxonomic division containing three groups of non-vascular land plants (embryophytes): the liverworts, hornworts and mosses. Bryophyta s.s. consists of the mosses only. They are characteristically limited in s ...
lineage.
Due to the very large genome seen in most ferns, it was suspected they might had gone through whole genome duplications, but DNA sequencing
DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, guanine, cytosine, and thymine. T ...
has shown that their genome size is caused by the accumulation of mobile DNA like transposons
A transposable element (TE, transposon, or jumping gene) is a nucleic acid sequence in DNA that can change its position within a genome, sometimes creating or reversing mutations and altering the cell's genetic identity and genome size. Tran ...
and other genetic elements that infect genomes and get copied over and over again.
Distribution and habitat
Ferns are widespread in their distribution, with the greatest richness in the tropics and least in arctic areas. The greatest diversity occurs in tropical rainforests. New Zealand, for which the fern is a symbol, has about 230 species, distributed throughout the country.
Ecology
Fern species live in a wide variety of habitat
In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
s, from remote mountain
A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited summit area, and is usually higher ...
elevations, to dry desert
A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About on ...
rock faces, bodies of water or open fields. Ferns in general may be thought of as largely being specialists in marginal habitats, often succeeding in places where various environmental factors limit the success of flowering plant
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants t ...
s. Some ferns are among the world's most serious weed species, including the bracken
Bracken (''Pteridium'') is a genus of large, coarse ferns in the family (biology), family Dennstaedtiaceae. Ferns (Pteridophyta) are vascular plants that have alternating generations, large plants that produce spores and small plants that produ ...
fern growing in the Scottish highlands, or the mosquito fern (''Azolla
''Azolla'' (mosquito fern, duckweed fern, fairy moss, water fern) is a genus of seven species of aquatic ferns in the family Salviniaceae. They are extremely reduced in form and specialized, looking nothing like other typical ferns but more rese ...
'') growing in tropical lakes, both species forming large aggressively spreading colonies. There are four particular types of habitats that ferns are found in: moist, shady forest
A forest is an area of land dominated by trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological function. The United Nations' ...
s; crevices in rock faces, especially when sheltered from the full sun; acid wetlands including bog
A bog or bogland is a wetland that accumulates peat as a deposit of dead plant materials often mosses, typically sphagnum moss. It is one of the four main types of wetlands. Other names for bogs include mire, mosses, quagmire, and muskeg; a ...
s and swamp
A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in ...
s; and tropical tree
In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
s, where many species are epiphyte
An epiphyte is an organism that grows on the surface of a plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphytes grow are called phoroph ...
s (something like a quarter to a third of all fern species).
Especially the epiphytic ferns have turned out to be hosts of a huge diversity of invertebrates. It is assumed that bird's-nest fern Bird's-nest fern is a common name applied to several related species of epiphytic ferns in the genus ''Asplenium
''Asplenium'' is a genus of about 700 species of ferns, often treated as the only genus in the family Aspleniaceae, though other aut ...
s alone contain up to half the invertebrate biomass within a hectare of rainforest
Rainforests are characterized by a closed and continuous tree canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforest can be classified as tropical rainforest or temperate rainfores ...
canopy.
Many ferns depend on associations with mycorrhizal
A mycorrhiza (from Greek μύκης ', "fungus", and ῥίζα ', "root"; pl. mycorrhizae, mycorrhiza or mycorrhizas) is a symbiotic association between a fungus and a plant. The term mycorrhiza refers to the role of the fungus in the pl ...
fungi. Many ferns grow only within specific pH ranges; for instance, the climbing fern ('' Lygodium palmatum'') of eastern North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...
will grow only in moist, intensely acid
In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a se ...
soils, while the bulblet bladder fern (''Cystopteris bulbifera
''Cystopteris bulbifera'', with the common name bulblet fern, bulblet bladderfern, or bulblet fragile fern is a fern in the family Cystopteridaceae.
Distribution
The fern is native to eastern Canada, the Midwestern and Eastern United States, a ...
''), with an overlapping range, is found only on limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms w ...
.
The spores are rich in lipid
Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids in ...
s, protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
and calories
The calorie is a unit of energy. For historical reasons, two main definitions of "calorie" are in wide use. The large calorie, food calorie, or kilogram calorie was originally defined as the amount of heat needed to raise the temperature of ...
, so some vertebrates eat these. The European woodmouse (''Apodemus sylvaticus'') has been found to eat the spores of ''Culcita macrocarpa
''Culcita macrocarpa'', the woolly tree fern, is a species of fern in the family Culcitaceae native to Macaronesia and parts of the Iberian Peninsula, where it might have been introduced.
Description
''Culcita macrocarpa'' is a large plant ...
'', and the bullfinch
Bullfinch is a name given to two groups of passerine birds.
True bullfinches
The true bullfinches are thick-billed finches in the passerine family Fringillidae. They comprise the genus ''Pyrrhula''. These birds are restricted to the Old World, an ...
(''Pyrrhula murina'') and the New Zealand lesser short-tailed bat
The New Zealand lesser short-tailed bat (''Mystacina tuberculata'') is a small-sized omnivorous mammal endemic to the islands of New Zealand. It is one of two extant and three overall terrestrial mammal species unique to New Zealand. The NZ lesse ...
(''Mystacina tuberculata'') also eat fern spores.
Life cycle
Ferns are vascular plant
Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They ...
s differing from lycophytes by having true leaves
A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, st ...
(megaphylls), which are often pinnate
Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, an ...
. They differ from seed plants (gymnosperm
The gymnosperms ( lit. revealed seeds) are a group of seed-producing plants that includes conifers, cycads, '' Ginkgo'', and gnetophytes, forming the clade Gymnospermae. The term ''gymnosperm'' comes from the composite word in el, γυμν ...
s and angiosperm
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants ...
s) in reproducing by means of spores and lacking flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechanis ...
s and seed
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosper ...
s. Like all land plants
The Embryophyta (), or land plants, are the most familiar group of green plants that comprise vegetation on Earth. Embryophytes () have a common ancestor with green algae, having emerged within the Phragmoplastophyta clade of green algae as siste ...
, they have a life cycle referred to as alternation of generations
Alternation of generations (also known as metagenesis or heterogenesis) is the predominant type of life cycle in plants and algae. It consists of a multicellular haploid sexual phase, the gametophyte, which has a single set of chromosomes alt ...
, characterized by alternating diploid
Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectiv ...
sporophytic
A sporophyte () is the diploid multicellular stage in the life cycle of a plant or alga which produces asexual spores. This stage alternates with a multicellular haploid gametophyte phase.
Life cycle
The sporophyte develops from the zygote pro ...
and haploid
Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respective ...
gametophytic phases. The diploid sporophyte has 2''n'' paired chromosome
A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins ar ...
s, where ''n'' varies from species to species. The haploid gametophyte has ''n'' unpaired chromosomes, i.e. half the number of the sporophyte. The gametophyte of ferns is a free-living organism, whereas the gametophyte of the gymnosperms and angiosperms is dependent on the sporophyte.
The life cycle of a typical fern proceeds as follows:
# A diploid sporophyte phase produces haploid spore
In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, ...
s by meiosis
Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately ...
(a process of cell division which reduces the number of chromosomes by a half).
# A spore grows into a free-living haploid gametophyte by mitosis
In cell biology, mitosis () is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is maintai ...
(a process of cell division which maintains the number of chromosomes). The gametophyte typically consists of a photosynthetic prothallus.
# The gametophyte produces gametes
A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during fertilization in organisms that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce ...
(often both sperm
Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as a flagellum, ...
and eggs on the same prothallus) by mitosis.
# A mobile, flagellate
A flagellate is a cell or organism with one or more whip-like appendages called flagella. The word ''flagellate'' also describes a particular construction (or level of organization) characteristic of many prokaryotes and eukaryotes and thei ...
sperm fertilizes an egg that remains attached to the prothallus.
# The fertilized egg is now a diploid zygote
A zygote (, ) is a eukaryotic cell formed by a fertilization event between two gametes. The zygote's genome is a combination of the DNA in each gamete, and contains all of the genetic information of a new individual organism.
In multicell ...
and grows by mitosis into a diploid sporophyte (the typical fern plant).
Uses
Ferns are not as important economically as seed plants, but have considerable importance in some societies. Some ferns are used for food, including the fiddleheads of ''Pteridium aquilinum'' (bracken
Bracken (''Pteridium'') is a genus of large, coarse ferns in the family (biology), family Dennstaedtiaceae. Ferns (Pteridophyta) are vascular plants that have alternating generations, large plants that produce spores and small plants that produ ...
), ''Matteuccia struthiopteris'' ( ostrich fern), and ''Osmundastrum cinnamomeum'' ( cinnamon fern). ''Diplazium esculentum
''Diplazium esculentum'', the vegetable fern, is an edible fern found throughout Asia and Oceania. It is probably the most commonly consumed fern.
The genus ''Diplazium'' is in the family Athyriaceae, in the eupolypods II clade of the order ...
'' is also used in the tropics (for example in ''budu pakis'', a traditional dish of Brunei
Brunei ( , ), formally Brunei Darussalam ( ms, Negara Brunei Darussalam, Jawi: , ), is a country located on the north coast of the island of Borneo in Southeast Asia. Apart from its South China Sea coast, it is completely surrounded by th ...
) as food. Tubers from the "para", ''Ptisana salicina
''Ptisana salicina'', or king fern, is a species of fern native to Norfolk Island, New Zealand and the South Pacific. Large and robust with a distinctive tropical appearance, it has fronds up to 5 metres (16 feet +/-) tall that arise from a st ...
'' (king fern) are a traditional food in New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island coun ...
and the South Pacific
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
. Fern tubers were used for food 30,000 years ago in Europe. Fern tubers were used by the Guanches
The Guanches were the indigenous inhabitants of the Canary Islands in the Atlantic Ocean some west of Africa.
It is believed that they may have arrived on the archipelago some time in the first millennium BCE. The Guanches were the only nativ ...
to make gofio in the Canary Islands
The Canary Islands (; es, :es:Canarias, Canarias, ), also known informally as the Canaries, are a Spanish Autonomous communities of Spain, autonomous community and archipelago in the Atlantic Ocean, in Macaronesia. At their closest point to ...
. Ferns are generally not known to be poisonous to humans. Licorice fern rhizome
In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow ...
s were chewed by the natives of the Pacific Northwest
The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Thou ...
for their flavor.
Ferns of the genus ''Azolla'', commonly known as water fern or mosquito ferns are very small, floating plants that do not resemble ferns. The mosquito ferns are used as a biological fertilizer in the rice paddies of southeast Asia, taking advantage of their ability to fix nitrogen from the air into compounds that can then be used by other plants.
Ferns have proved resistant to phytophagous insects. The gene that express the protein Tma12 in an edible fern, '' Tectaria macrodonta'', has been transferred to cotton plants, which became resistant to whitefly
Whiteflies are Hemipterans that typically feed on the undersides of plant leaves. They comprise the family Aleyrodidae, the only family in the superfamily Aleyrodoidea. More than 1550 species have been described.
Description and taxonomy
The ...
infestations.
Many ferns are grown in horticulture
Horticulture is the branch of agriculture that deals with the art, science, technology, and business of plant cultivation. It includes the cultivation of fruits, vegetables, nuts, seeds, herbs, sprouts, mushrooms, algae, flowers, seaweeds and no ...
as landscape plants, for cut foliage and as houseplant
A houseplant, sometimes known as a pot plant, potted plant, or an indoor plant, is an ornamental plant that is grown indoors. As such, they are found in places like residences and offices, mainly for decorative purposes. Common houseplants are us ...
s, especially the Boston fern ('' Nephrolepis exaltata'') and other members of the genus '' Nephrolepis''. The bird's nest fern (''Asplenium nidus'') is also popular, as are the staghorn ferns (genus ''Platycerium''). Perennial (also known as hardy) ferns planted in gardens in the northern hemisphere also have a considerable following.
Several ferns, such as bracken and ''Azolla'' species are noxious weed
A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...
s or invasive species
An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species adv ...
. Further examples include Japanese climbing fern ('' Lygodium japonicum''), sensitive fern (''Onoclea sensibilis'') and Giant water fern ('' Salvinia molesta''), one of the world's worst aquatic weeds. The important fossil fuel coal
Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen.
Coal is formed when ...
consists of the remains of primitive plants, including ferns.
Ferns have been studied and found to be useful in the removal of heavy metals, especially arsenic, from the soil. Other ferns with some economic significance include:
* '' Dryopteris filix-mas'' (male fern), used as a vermifuge
Anthelmintics or antihelminthics are a group of antiparasitic drugs that expel parasitic worms (helminths) and other internal parasites from the body by either stunning or killing them and without causing significant damage to the host. They may ...
, and formerly in the US Pharmacopeia; also, this fern accidentally sprouting in a bottle resulted in Nathaniel Bagshaw Ward
Nathaniel Bagshaw Ward (1791 – 4 June 1868 in St Leonard's, Sussex) was an English doctor who popularised a case for growing and transporting plants which was called the Wardian case.
Biography
Ward was born in London to Stephen Smith W ...
's 1829 invention of the terrarium or Wardian case
* '' Rumohra adiantiformis'' (floral fern), extensively used in the florist
Floristry is the production, commerce, and trade in flowers. It encompasses flower care and handling, floral design and arrangement, merchandising, production, display and flower delivery. Wholesale florists sell bulk flowers and related su ...
trade
* '' Microsorum pteropus'' (Java fern), one of the most popular freshwater aquarium plants.
* '' Osmunda regalis'' (royal fern) and ''Osmunda cinnamomea
''Osmundastrum'' is genus of leptosporangiate ferns in the family Osmundaceae with one living species, ''Osmundastrum cinnamomeum'', the cinnamon fern. It is native to the Americas and eastern Asia, growing in swamps, bogs and moist woodlands.
I ...
'' (cinnamon fern), the root fiber being used horticulturally; the fiddleheads of ''O. cinnamomea'' are also used as a cooked vegetable
* ''Matteuccia struthiopteris
''Matteuccia'' is a genus of ferns with one species: ''Matteuccia struthiopteris'' (common names ostrich fern, fiddlehead fern, or shuttlecock fern). The species epithet ''struthiopteris'' comes from Ancient Greek words () "ostrich" and () "fer ...
'' (ostrich fern), the fiddleheads used as a cooked vegetable in North America
* '' Pteridium aquilinum'' and ''Pteridium esculentum
''Pteridium esculentum'', commonly known as bracken fern, Austral bracken or simply bracken, is a species of the bracken genus native to a number of countries in the Southern Hemisphere. Esculentum means edible. First described as ''Pteris escu ...
'' (bracken), the fiddleheads used as a cooked vegetable in Japan and are believed to be responsible for the high rate of stomach cancer in Japan. It is also one of the world's most important agricultural weeds, especially in the British highlands, and often poisons cattle and horses.
* ''Diplazium esculentum
''Diplazium esculentum'', the vegetable fern, is an edible fern found throughout Asia and Oceania. It is probably the most commonly consumed fern.
The genus ''Diplazium'' is in the family Athyriaceae, in the eupolypods II clade of the order ...
'' (vegetable fern), a source of food for some societies
* ''Pteris vittata
''Pteris vittata'', commonly known variously as the Chinese brake, Chinese ladder brake, or simply ladder brake, is a fern species in the Pteridoideae subfamily of the Pteridaceae. It is indigenous to Asia, southern Europe, tropical Africa and ...
'' (brake fern), used to absorb arsenic
Arsenic is a chemical element with the symbol As and atomic number 33. Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid. It has various allotropes, b ...
from the soil
* ''Polypodium glycyrrhiza
''Polypodium glycyrrhiza'', commonly known as licorice fern, many-footed fern, and sweet root, is a summer deciduous fern native to western North America, where it is found in shaded, damp locations.
Spores are located in rounded sori on the ...
'' (licorice fern), roots chewed for their pleasant flavor
* Tree ferns, used as building material in some tropical areas
* ''Cyathea cooperi
''Sphaeropteris cooperi'', synonym ''Cyathea cooperi'', also known as lacy tree fern, scaly tree fern, or Cooper's tree fern, is a tree fern native to Australia, in New South Wales and Queensland.
Description
''Sphaeropteris cooperi'' is a m ...
'' (Australian tree fern), an important invasive species in Hawaii
* ''Ceratopteris richardii
''Ceratopteris richardii'' is a fern species belonging to the genus '' Ceratopteris'', one of only two genera of the subfamily Parkerioideae of the family Pteridaceae. It is one of several genera of ferns adapted to an aquatic existence. ''C. r ...
'', a model plant for teaching and research, often called C-fern
Culture
Pteridologist
The study of ferns and other pteridophytes is called pteridology. A pteridologist is a specialist in the study of pteridophytes in a broader sense that includes the more distantly related lycophytes.
Pteridomania
Pteridomania
Pteridomania or fern fever was a Victorian craze for ferns. Decorative arts of the period presented the fern motif in pottery, glass, metal, textiles, wood, printed paper, and sculpture, with ferns "appearing on everything from christening ...
is a term for the Victorian era
In the history of the United Kingdom and the British Empire, the Victorian era was the period of Queen Victoria's reign, from 20 June 1837 until her death on 22 January 1901. The era followed the Georgian period and preceded the Edwa ...
craze of fern collecting
The hobby of collecting includes seeking, locating, acquiring, organizing, cataloging, displaying, storing, and maintaining items that are of interest to an individual ''collector''. Collections differ in a wide variety of respects, most obvi ...
and fern motifs in decorative art
]
The decorative arts are arts or crafts whose object is the design and manufacture of objects that are both beautiful and functional. It includes most of the arts making objects for the interiors of buildings, and interior design, but not usua ...
including pottery
Pottery is the process and the products of forming vessels and other objects with clay and other ceramic materials, which are fired at high temperatures to give them a hard and durable form. Major types include earthenware, stoneware and ...
, glass
Glass is a non- crystalline, often transparent, amorphous solid that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by rapid cooling (quenchin ...
, metal
A metal (from ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electrical resistivity and conductivity, e ...
s, textile
Textile is an Hyponymy and hypernymy, umbrella term that includes various Fiber, fiber-based materials, including fibers, yarns, Staple (textiles)#Filament fiber, filaments, Thread (yarn), threads, different #Fabric, fabric types, etc. At f ...
s, wood
Wood is a porous and fibrous structural tissue found in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulose fibers that are strong in tension and embedded in a matrix of lignin ...
, printed paper, and sculpture
Sculpture is the branch of the visual arts that operates in three dimensions. Sculpture is the three-dimensional art work which is physically presented in the dimensions of height, width and depth. It is one of the plastic arts. Durable ...
"appearing on everything from christening presents to gravestones and memorials." The fashion for growing ferns indoors led to the development of the Wardian case, a glazed cabinet that would exclude air pollutants and maintain the necessary humidity.
The dried form of ferns was also used in other arts, being used as a stencil or directly inked for use in a design. The botanical work, ''The Ferns of Great Britain and Ireland
''The Ferns of Great Britain and Ireland'' was a book published in 1855 that featured 51 plates of nature printing by Henry Bradbury.
Description
The text was a scientific description of all the varieties of Ferns found in the British Isles. The ...
'', is a notable example of this type of nature printing Nature printing is a printing process, developed in the 18th century, that uses the plants, animals, rocks and other natural subjects to produce an image. The subject undergoes several stages to give a direct impression onto materials such as lead, ...
. The process, patented by the artist and publisher Henry Bradbury, impressed a specimen on to a soft lead plate. The first publication to demonstrate this was Alois Auer's ''The Discovery of the Nature Printing-Process''.
Fern bars were popular in America in the 1970s and 80s.
Folklore
Ferns figure in folklore, for example in legends about mythical flowers or seeds. In Slavic folklore
Slavic folklore encompasses the folklore of the Slavic peoples from their earliest records until today. Folklorists have published a variety of works focused specifically on the topic over the years.See, for example, Kononenko 2007.
See also
* ...
, ferns are believed to bloom once a year, during the Ivan Kupala
Kupala Night ( be, Купалле, pl, Noc Kupały, russian: Иван-Купала, uk, Івана Купала, Купайла), also called Ivanа Kupala, is a traditional Slavic holiday that was originally celebrated on the shortest night of ...
night. Although alleged to be exceedingly difficult to find, anyone who sees a fern flower
The fern flower is a magic flower in Baltic mythology ( lt, paparčio žiedas, lv, papardes zieds), in Estonian mythology ( et, sõnajalaõis) and in Slavic mythology ( be, папараць-кветка, pl, kwiat paproci, russian: цвет� ...
is thought to be guaranteed to be happy and rich for the rest of their life. Similarly, Finnish tradition holds that one who finds the seed
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosper ...
of a fern in bloom on Midsummer
Midsummer is a celebration of the season of summer usually held at a date around the summer solstice. It has pagan pre-Christian roots in Europe.
The undivided Christian Church designated June 24 as the feast day of the early Christian martyr ...
night will, by possession of it, be guided and be able to travel invisibly to the locations where eternally blazing Will o' the wisp
In folklore, a will-o'-the-wisp, will-o'-wisp or ''ignis fatuus'' (, plural ''ignes fatui''), is an atmospheric ghost light seen by travellers at night, especially over bogs, swamps or marshes. The phenomenon is known in English folk belief, ...
s called aarnivalkea mark the spot of hidden treasure
Treasure (from la, thesaurus from Greek language ''thēsauros'', "treasure store") is a concentration of wealth — often originating from ancient history — that is considered lost and/or forgotten until rediscovered. Some jurisdictions le ...
. These spots are protected by a spell that prevents anyone but the fern-seed holder from ever knowing their locations. In the US, ferns are thought to have magical properties such as a dried fern can be thrown into hot coals of a fire to exorcise evil spirits, or smoke from a burning fern is thought to drive away snakes and such creatures.
New Zealand
Ferns are the national emblem of New Zealand and feature on its passport and in the design of its national airline, Air New Zealand
Air New Zealand Limited () is the flag carrier airline of New Zealand. Based in Auckland, the airline operates scheduled passenger flights to 20 domestic and 30 international destinations in 18 countries, primarily around and within the Pacif ...
, and its rugby team, the All Blacks
The New Zealand national rugby union team, commonly known as the All Blacks ( mi, Ōpango), represents New Zealand in men's international rugby union, which is considered the country's national sport. The team won the Rugby World Cup in 1987, ...
.
Organisms confused with ferns
Misnomers
Several non-fern plants (and even animals) are called ferns and are sometimes confused with ferns. These include:
* Asparagus fern—This may apply to one of several species of the monocot
Monocotyledons (), commonly referred to as monocots, (Lilianae '' sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one ...
genus ''Asparagus
Asparagus, or garden asparagus, folk name sparrow grass, scientific name ''Asparagus officinalis'', is a perennial flowering plant species in the genus '' Asparagus''. Its young shoots are used as a spring vegetable.
It was once classified in ...
'', which are flowering plants.
* Sweetfern—A flowering shrub of the genus '' Comptonia''.
* Air fern—A group of animal
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage ...
s called hydrozoa
Hydrozoa (hydrozoans; ) are a taxonomic class of individually very small, predatory animals, some solitary and some colonial, most of which inhabit saline water. The colonies of the colonial species can be large, and in some cases the specialize ...
n that are distantly related to jellyfish
Jellyfish and sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbre ...
and coral
Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and se ...
s. They are harvested, dried, dyed green, and then sold as a plant that can live on air. While it may look like a fern, it is merely the skeleton of this colonial animal.
* Fern bush—'' Chamaebatiaria millefolium''—a rose family shrub with fern-like leaves.
* Fern tree—''Jacaranda mimosifolia
''Jacaranda mimosifolia'' is a sub-tropical tree native to south-central South America that has been widely planted elsewhere because of its attractive and long-lasting violet-colored flowers. It is also known as the jacaranda, blue jacaranda, ...
''—an ornamental tree
Ornamental plants or garden plants are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars that ...
of the order Lamiales
The order Lamiales (also known as the mint order) are an order in the asterid group of dicotyledonous flowering plants. It includes about 23,810 species, 1,059 genera, and is divided into about 25 families. These families include Acanthaceae, Big ...
.
* Fern leaf tree—'' Filicium decipiens''—an ornamental tree
Ornamental plants or garden plants are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars that ...
of the order Sapindales.
Fern-like flowering plants
Some flowering plant
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants t ...
s such as palms and members of the carrot family have pinnate
Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, an ...
leaves that somewhat resemble fern fronds. However, these plants have fully developed seeds contained in fruits, rather than the microscopic spores of ferns.
Gallery
File:CowellFerns.JPG, Ferns in one of many natural Coast Redwood undergrowth settings Santa Cruz, CA
Santa Cruz ( Spanish for "Holy Cross") is the county seat and largest city of Santa Cruz County, in Northern California. As of the 2020 census, the city population was 62,956. Situated on the northern edge of Monterey Bay, Santa Cruz is a pop ...
File:FernBedInForest.jpg, Fern bed under a forest canopy in woods near Franklin, Virginia
File:Samambaia fern.jpg, Fern growing on a wall
File:Silver-fern.jpg, Silver fern or ''Alsophila dealbata'', endemic to New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island coun ...
File:Adiantum lunulatum W IMG 2336.jpg, '' Adiantum philippense''
File:Pyrrosia piloselloides duit-duit.jpg, ', dragon's scale, in Malaysia
File:Kidney Fern New Zealand. (12185571965).jpg, '' Hymenophyllum nephrophyllum'', the kidney fern
File:Fern02.jpg, Tree fern, probably ''Dicksonia antarctica
''Dicksonia antarctica'', the soft tree fern or man fern, is a species of evergreen tree fern native to eastern Australia, ranging from south-east Queensland, coastal New South Wales and Victoria to Tasmania.
Anatomy and biology
These ferns ...
''
File:Ferns.jpg, Tree ferns, probably ''Dicksonia antarctica''
File:Haeckel Filicinae 92.jpg, "Filicinae" from Ernst Haeckel
Ernst Heinrich Philipp August Haeckel (; 16 February 1834 – 9 August 1919) was a German zoologist, naturalist, eugenicist, philosopher, physician, professor, marine biologist and artist. He discovered, described and named thousands of new s ...
's ''Kunstformen der Natur
(known in English as ''Art Forms in Nature'') is a book of lithographic and halftone prints by German biologist Ernst Haeckel.
...
'', 1904
File:Spiraled fern.JPG, A young, newly formed fern frond
File:Tree Fern.jpg, A tree fern unrolling a new frond
File:Fern.jpg, Fern leaf, probably ''Lomaria nuda
''Lomaria nuda'', commonly known as the fishbone waterfern, is a fern that grows up to a metre tall, and is abundant in rainforest and eucalyptus forests in eastern Australia. The species is placed in the genus '' Lomaria'' in the Pteridophyt ...
''
File:Fern-leaf-oliv.jpg, Leaf of fern
File:Asplenium marinum Moore38.png, Nature prints in The Ferns of Great Britain and Ireland
''The Ferns of Great Britain and Ireland'' was a book published in 1855 that featured 51 plates of nature printing by Henry Bradbury.
Description
The text was a scientific description of all the varieties of Ferns found in the British Isles. The ...
used fronds to produce the plates
File:Fern Spores.jpg, Sporangia
A sporangium (; from Late Latin, ) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other lineages form sporangia at some point in their life cy ...
of '' Dryopteris filix-mas''
File:Tree Fern Spores.jpg, Tree fern sporangia San Diego, CA
File:蕨類 Fern 20220406200725 02.jpg, Sporangia on a leaflet
File:Fern fiddleheads.jpg
File:臺灣粗榧 - 溪頭自然教育園區 Cephalotaxus wilsoniana - Xitou Nature Education Area, Taiwan 20220316205506 21.jpg, Epiphytic fern on the branch of '' Cephalotaxus wilsoniana''
See also
* British Pteridological Society
* Chirosia betuleti - Fern gall
* Fern spike
* Fern sports
* Paisley (design)
Paisley or paisley pattern is an ornamental textile design using the ''boteh'' ( fa, بته) or ''buta'', a teardrop-shaped motif with a curved upper end. Of Persian origin, paisley designs became popular in the West in the 18th and 19th centur ...
* Pteridophyte
A pteridophyte is a vascular plant (with xylem and phloem) that disperses spores. Because pteridophytes produce neither flowers nor seeds, they are sometimes referred to as " cryptogams", meaning that their means of reproduction is hidden. Fer ...
* Silver fern flag
Notes
References
Bibliography
Books and theses
*
* , ''see also'' Species Plantarum
' (Latin for "The Species of Plants") is a book by Carl Linnaeus, originally published in 1753, which lists every species of plant known at the time, classified into genera. It is the first work to consistently apply binomial names and was the ...
* Lord, Thomas R. (2006). ''Ferns and Fern Allies of Pennsylvania''. Indiana, PA: Pinelands Press
Ferns and Fern Allies of Pennsylvania - Thomas Reeves Lord
* Moran, Robbin C. (2004). ''A Natural History of Ferns''. Portland, OR: Timber Press. .
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Journal articles
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Websites
*
*
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* A classification of th
L. Watson and M.J. Dallwitz (2004 onwards). The Ferns (Filicopsida) of the British Isles.
"American Fern Society"
"British Pteridological Society"
Images of ferns of Hawaii
External links
*
*
{{Authority control
Non-timber forest products
Extant Late Devonian first appearances