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A spermatophyte (; ), also known as phanerogam (taxon Phanerogamae) or phaenogam (taxon Phaenogamae), is any
plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae excl ...
that produces
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, hence the alternative name seed plant. Spermatophytes are a subset of the
embryophyte 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 sis ...
s or land plants. They include most familiar types of plants, including all
flowers 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 mechanism ...
and most trees, but exclude some other types of plants such as ferns, mosses, algae. The term ''phanerogams'' or ''phanerogamae'' is derived from the Greek (), meaning "visible", in contrast to the cryptogamae (), together with the
suffix In linguistics, a suffix is an affix which is placed after the stem of a word. Common examples are case endings, which indicate the grammatical case of nouns, adjectives, and verb endings, which form the conjugation of verbs. Suffixes can carr ...
(), meaning "to marry". These terms distinguished those plants with hidden sexual organs (cryptogamae) from those with visible sexual organs (phanerogamae).


Description

The extant spermatophytes form five divisions, the first four of which are traditionally grouped as
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, plants that have unenclosed, "naked seeds": * Cycadophyta, the cycads, a subtropical and tropical group of plants, * Ginkgophyta, which includes a single living species of tree in the genus '' Ginkgo'', * Pinophyta, the conifers, which are cone-bearing trees and shrubs, and *
Gnetophyta Gnetophyta () is a division of plants (alternatively considered the subclass Gnetidae or order Gnetales), grouped within the gymnosperms (which also includes conifers, cycads, and ginkgos), that consists of some 70 species across the three ...
, the gnetophytes, various woody plants in the relict genera '' Ephedra'', ''
Gnetum ''Gnetum'' is a genus of gymnosperms, the sole genus in the family Gnetaceae within the Gnetophyta. They are tropical evergreen trees, shrubs and lianas. Unlike other gymnosperms, they possess vessel elements in the xylem. Some species have been ...
'', and '' Welwitschia''. The fifth extant division is the
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, also known as angiosperms or magnoliophytes, the largest and most diverse group of spermatophytes: *
Angiosperms 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 ...
, the flowering plants, possess seeds enclosed in a
fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in partic ...
, unlike gymnosperms. In addition to the five living taxa listed above, the fossil record contains evidence of many extinct taxa of seed plants, among those: *
Pteridospermae The term Pteridospermatophyta (or "seed ferns" or "Pteridospermatopsida") is a polyphyletic group of extinct seed-bearing plants (spermatophytes). The earliest fossil evidence for plants of this type is the genus ''Elkinsia'' of the late Devonian ...
, the so-called "seed ferns", were one of the earliest successful groups of land plants, and forests dominated by seed ferns were prevalent in the late
Paleozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ...
. * '' Glossopteris'' was the most prominent tree genus in the ancient southern supercontinent of Gondwana during the
Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleo ...
period. 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 ...
period, seed ferns had declined in ecological importance, and representatives of modern gymnosperm groups were abundant and dominant through the end of the
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 the
angiosperms 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 ...
radiated.


Evolutionary history

A whole genome duplication event in the ancestor of seed plants occurred about .Jiao Y, Wickett NJ, Ayyampalayam S, Chanderbali AS, Landherr L, Ralph PE, Tomsho LP, Hu Y, Liang H, Soltis PS, Soltis DE, Clifton SW, Schlarbaum SE, Schuster SC, Ma H, Leebens-Mack J, Depamphilis CW (2011) Ancestral polyploidy in seed plants and angiosperms. Nature This gave rise to a series of evolutionary changes that resulted in the origin of seed plants. A middle Devonian (385-million-year-old)
precursor Precursor or Precursors may refer to: * Precursor (religion), a forerunner, predecessor ** The Precursor, John the Baptist Science and technology * Precursor (bird), a hypothesized genus of fossil birds that was composed of fossilized parts of u ...
to seed plants from
Belgium Belgium, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to ...
has been identified predating the earliest seed plants by about 20 million years. ''
Runcaria ''Runcaria heinzelinii'' is an extinct species of plant from the Middle Devonian of Belgium. It is the only species classified under the genus ''Runcaria'', named after Jean de Heinzelin de Braucourt. It was a precursor to seed plants, predating ...
'', small and radially symmetrical, is an integumented megasporangium surrounded by a cupule. The megasporangium bears an unopened distal extension protruding above the mutlilobed integument. It is suspected that the extension was involved in anemophilous (wind)
pollination Pollination is the transfer of pollen from an Stamen, anther of a plant to the stigma (botany), stigma of a plant, later enabling fertilisation and the production of seeds, most often by an animal or by Anemophily, wind. Pollinating agents can ...
. ''Runcaria'' sheds new light on the sequence of character acquisition leading to the seed. ''Runcaria'' has all of the qualities of seed plants except for a solid seed coat and a system to guide the pollen to the seed.


Relationships and nomenclature

Seed-bearing plants are a subclade of the vascular plants (tracheophytes) and were traditionally divided into angiosperms, or flowering plants, and
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, which includes the gnetophytes, cycads, ginkgo, and conifers. Older morphological studies believed in a close relationship between the gnetophytes and the angiosperms, in particular based on vessel elements. However, molecular studies (and some more recent morphological and fossil papers) have generally shown a clade of
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, with the gnetophytes in or near the conifers. For example, one common proposed set of relationships is known as the ''gne-pine hypothesis'' and looks like: However, the relationships between these groups should not be considered settled. Other classifications group all the seed plants in a single division, with classes for the five groups: *Division Spermatophyta ** Cycadopsida, the cycads ** Ginkgoopsida, the ginkgo **
Pinopsida Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All extan ...
, the conifers, ("Coniferopsida") **
Gnetopsida Gnetophyta () is a division of plants (alternatively considered the subclass Gnetidae or order Gnetales), grouped within the gymnosperms (which also includes conifers, cycads, and ginkgos), that consists of some 70 species across the three rel ...
, the gnetophytes ** Magnoliopsida, the
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, or Angiospermopsida A more modern classification ranks these groups as separate divisions (sometimes under the Superdivision Spermatophyta): * Cycadophyta, the cycads * Ginkgophyta, the ginkgo * Pinophyta, the conifers *
Gnetophyta Gnetophyta () is a division of plants (alternatively considered the subclass Gnetidae or order Gnetales), grouped within the gymnosperms (which also includes conifers, cycads, and ginkgos), that consists of some 70 species across the three ...
, the gnetophytes * Magnoliophyta, the
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 An alternative phylogeny of spermatophytes based on the work by Novíkov & Barabaš-Krasni 2015 with plant taxon authors from Anderson, Anderson & Cleal 2007 showing the relationship of extinct clades. Unassigned spermatophytes: * † Avatiaceae Anderson & Anderson 2003 * † Axelrodiopsida Anderson & Anderson * † Alexiales Anderson & Anderson 2003 * † Hamshawviales Anderson & Anderson 2003 * † Hexapterospermales Doweld 2001 * † Hlatimbiales Anderson & Anderson 2003 * † Matatiellales Anderson & Anderson 2003 * † Petriellales Taylor et al. 1994 * † Arberiopsida Doweld 2001 * †
Czekanowskiales Czekanowskiales, also known as Leptostrobales, are an extinct group of seed plants. Members of the family are distinguished by persistent leaves borne on deciduous short shoots, subtended by scale-like leaves. The leaves are highly dissected (div ...
Taylor et al. 2008 * † Iraniales E. Taylor et al. 2008 * † Vojnovskyales E. Taylor et al. 2008 * † Hermanophytales E. Taylor et al. 2008 * † Dirhopalostachyaceae E. Taylor et al. 2008


References


Bibliography

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