''Polystichum acrostichoides'', commonly denominated Christmas fern, is a

perennial 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 wide ...

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, which ...

fern 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 except ...

native to eastern North America, from

Nova Scotia Nova Scotia ( ; ; ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. Nova Scotia is Latin for "New Scotland". Most of the population are native En ...

west to

Minnesota Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the List of U.S. states and territories by population, 22nd most populous, with over 5.75 million residents. Minne ...

and south to

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, a ...

and eastern

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

.USDA
accessed 2011. It is one of the most common ferns in eastern North America, being found in moist and shady habitats in woodlands, stream banks and rocky slopes. The common name derives from the

fronds, which are often still green at

Christmas Christmas is an annual festival commemorating the birth of Jesus Christ, observed primarily on December 25 as a religious and cultural celebration among billions of people around the world. A feast central to the Christian liturgical year ...

Description

Christmas fern has a tufted, clumping

habit A habit (or wont as a humorous and formal term) is a routine of behavior that is repeated regularly and tends to occur subconsciously.

, with its fronds arising from a central growth point. It can form colonies, but frequently grows singly or in twos or threes. In winter, the fertile fronds die; the sterile fronds remain through the winter, and are often flattened to the ground by low temperatures and snow cover. The frond is supported by a dark brown- to black-colored stipe, or stem, which is typically a quarter to a third of the overall frond length. Coarse, light-brown-to-tan scales cover the stipe, and are typically about and translucent. The coiled, developing fronds (" crosiers") are scaly, greyish and prominent in early spring. Fronds are and , dark green and rather leathery in texture; their undersides may be covered in very sparse hairs. They have 20 to 35 pairs of pinnae. Each pinna is typically and has a finely serrulate or spiny edge, and is oblong to

falcate The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular o ...

in shape. The fine teeth or spines on the edge of the pinna are oriented towards its tip. Each pinna has a small, triangular, "thumblike" lobe at its base. The light brown

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 are produced on fertile pinnae, at the frond's tip, which are conspicuously smaller than the sterile pinnae further down the frond. These fertile pinnae can be described as " acrostichoid", given that the

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 cyc ...

occupy most of the lower surface of the pinna. Christmas fern resembles the Pacific Coast sword fern, '' Polystichum munitum'', although forming less expansive tufts and differing from it and from almost all other ferns in that fertile pinnae of the Christmas fern are noticeably reduced in size relative to the sterile pinnae, while being located on the same frond. ''P. acrostichoides'' is known to hybridize with ''

Polystichum braunii Braun's hollyfern (''Polystichum braunii'') is a species of '' Polystichum''. It is native to Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemisp ...

'' in areas where their ranges overlap. ''P. acrostichoides'' is

parasitized Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

by the fungus ''

Taphrina polystichi ''Taphrina polystichi'' is an ascomycete fungus that parasitizes Christmas fern ('' Polystichum acrostichoides'') in eastern North America. It was described by A. J. Mix in 1938. Taxonomy ''Taphrina polystichi'' was described in A. J. Mix in 1 ...

'', which causes yellowish to whitish galls on the fronds.

Cultivation

fern is popular in cultivation as an

ornamental plant 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 ...

for

garden A garden is a planned space, usually outdoors, set aside for the cultivation, display, and enjoyment of plants and other forms of nature. The single feature identifying even the wildest wild garden is ''control''. The garden can incorporate bot ...

s, including natural gardens, as it is easy to cultivate in a range of environments and soils. Being evergreen, it sometimes used in winter-oriented

garden design Garden design is the art and process of designing and creating plans for layout and planting of gardens and landscapes. Garden design may be done by the garden owner themselves, or by professionals of varying levels of experience and expertise. ...

. This fern can conserve soil and allay erosion of steep slopes. The fronds are semi-erect until the first killing frost, after which they lie prostrate on the ground and effectively hold in place the

duff Duff may refer to: People * Duff (surname) * Duff (given name) * Duff (nickname) * Karen Duffy, an actress, model, and former MTV VJ once known as "Duff" * Duff Roman, on-air name of Canadian radio personality and executive David Mostoway (bo ...

layer of the forest floor, enabling the gradual

decomposition Decomposition or rot is the process by which dead organic substances are broken down into simpler organic or inorganic matter such as carbon dioxide, water, simple sugars and mineral salts. The process is a part of the nutrient cycle and is ...

of the duff into

humus In classical soil science, humus is the dark organic matter in soil that is formed by the decomposition of plant and animal matter. It is a kind of soil organic matter. It is rich in nutrients and retains moisture in the soil. Humus is the Lati ...

, which in turn builds the soil.

Gallery

Image:Christmas Fern Polystichum acrostichoides Curl Closeup 2000xpx.jpg, Coiled immature fronds Image:Christmas Fern Polystichum acrostichoides Unfurled 2000px.jpg, Newly unfurled frond Image:Christmas Fern Polystichum acrostichoides Leaf 2000px.JPG, Mature sterile frond File:Polystichum acrostichoides5.jpg, Sori

References

External links

*
USDA PLANTS Profile for ''Polystichum acrostichoides'' (Christmas fern)

Flora of North America: ''Polystichum acrostichoides''

Flora of PA: ''Polystichum acrostichoides''
{{Taxonbar, from=Q7226975 acrostichoides Garden plants of North America Ferns of the Americas Ferns of the United States