Braun's holly fern (Polystichum braunii)
|Also known as:||Braun's hollyfern, Braun's sword fern, eastern holly fern, prickly shield fern|
|Synonyms:||Aspidium braunii, Dryopteris braunii|
Braun's holly fern has not yet been assessed by the IUCN.
Braun’s holly fern (Polystichum braunii) is a relatively large fern found across northern regions of North America, Europe and Asia. Its stem, which is actually an above-ground rhizome, is short, stout, erect and covered in pale brown scales (2) (3) (4). The evergreen frond is shiny green, tapers at the base and tip and is divided into leaflets (2) (4), which are themselves divided into smaller leaflets known as ‘pinnules’ (5). The pinnules of Braun’s holly fern have serrated margins bearing bristle-edged teeth (6).
Braun’s holly fern occurs in the northern forests that stretch across North America and Europe, across to Russia and Siberia (3).
In North America, this species ranges from Alaska, the Yukon, British Colombia, Newfoundland and Ontario in Canada, south to Idaho, Minnesota, Wisconsin, Michigan, New York and Massachusetts in the United States (4).
Braun’s holly fern is most typically found in cool, moist, shaded places in boreal forest and northern hardwood deciduous forests, but also occurs on rocky slopes and moist cliffs (2) (6) (7).
Ferns are ‘primitive’ plants that spread by releasing spores rather than by producing flowers and fruits. The distinctive frond stage of the fern lifecycle is asexual; spores are released from the fronds, which then germinate into minuscule heart-shaped structures known as ‘prothalli’. It is here that the sexual stage of the lifecycle occurs; male and female organs on the prothallus produce sperm and eggs respectively. If the eggs are fertilised successfully, a new fern plant will begin to grow and the cycle starts again (5)
Braun’s holly fern is considered to be rare in parts of its range, such as the eastern U.S. (6), in part due to its sensitivity to logging (4). However, very little is known about the conservation status of this species and the threats it faces, and it has yet to be assessed by the IUCN (8).
There are no known specific conservation measures currently in place for Braun’s holly fern.
Find out more about Braun’s holly fern:
Hardy Fern Library - Braun’s holly fern:
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- Asexual reproduction: reproduction that does not involve the formation of sex cells (‘gametes’). In many species, asexual reproduction can occur by existing cells splitting into two, or part of the organism breaking away and developing into a separate individual. Some animals, including vertebrates, can also develop from unfertilised eggs; this process, known as parthenogenesis, gives rise to offspring that are genetically identical to the parent.
- Boreal forest: the sub-Arctic forest of the high northern latitudes that surrounds the North Pole and is mainly composed of coniferous trees.
- Deciduous forest: forest consisting mainly of deciduous trees, which shed their leaves at the end of the growing season.
- Evergreen: a plant which retains leaves all year round. This is in contrast to deciduous plants, which completely lose their leaves for part of the year.
- Fertilisation: the fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.
- Germination: the beginning of growth, usually following a period of dormancy and in response to favourable conditions. For example, the sprouting of a seedling from a seed.
- Prothallus: in ferns and other primitive plants, a small, gamete-producing structure (gametophyte) that germinates from a spore.
- Rhizome: an underground, horizontal plant stem that produces roots and shoots.
- Spores: microscopic particles produced by many non-flowering plants and fungi that are capable of developing into a new individual. Spores are adapted for dispersal and surviving for long periods of time in unfavourable conditions.
UNEP-WCMC (July, 2011)
Hardy Fern Library - Braun’s holly fern, Polystichum braunii (July, 2011)
- Olsen, S. and Olsen, S. (2007) Encyclopedia of Garden Ferns. Timber Press, Oregon.
Ferns and Fern Allies of the Northwoods - Braun's Holly Fern, Polystichum braunii (July, 2011)
Australian National Herbarium (July, 2011)
- Coffin, B. and Pfannmuller, L. (1988) Minnesota's Endangered Flora and Fauna. University of Minnesota Press, Minnesota.
Flora of North America - Polystichum braunii (July, 2011)
IUCN Red List (July, 2011)