Polytrichum

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Polytrichum
Male
antheridia
Scientific classification Edit this classification
Kingdom: Plantae
Division: Bryophyta
Class: Polytrichopsida
Order: Polytrichales
Family: Polytrichaceae
Genus: Polytrichum
Hedw.

Polytrichum is a genus of mosses — commonly called haircap moss or hair moss — which contains approximately 70 species that have a cosmopolitan distribution. The genus Polytrichum has a number of closely related

Norse Mythology, wife of the god Thor. There are two major sections of Polytrichum species. The first — section Polytrichum — has narrow, toothed, and relatively erect leaf margins. The other — section Juniperifolia — has broad, entire, and sharply inflexed leaf margins that enclose the lamellae on the upper leaf surface.[1][2]

Anatomy of Polytrichum formosum plant.

Appearance

Haircap moss gets its name from the hairs that cover, or cap, the calyptra where each spore case is held (1). Looking down, haircap moss has a star-shaped appearance due to its pointed leaves arranged spirally at right angles around a stiff stem (3). It is generally dark green in color and grows 4 – 20 cm tall. The average life span of this moss is three to five years, though the longest have lived up to ten, and the moss can remain intact for long periods after dead.

Physiology

Mosses in the genus Polytrichum are endohydric, meaning water is conducted from the base of the plant. While mosses are considered

analogous to xylem in higher plants. The other tissue is called leptome, which surrounds the hydrome, contains smaller cells and is analogous to phloem.[3]

chloroplasts
.

Another characteristic feature of the genus is its parallel

fungi and rotifers. Additionally, the leaves will curve and then twist around the stem when conditions become too dry, this being another xeromorphic adaptation. It is speculated that the teeth along the leaf's edge may aid in this process, or perhaps also that they help discourage small invertebrates from attacking the leaves.[3]

Polytrichum species are

dioicous, having separate male and female plants. The reproductive branches arise from the apex of the main gametophyte axis.[citation needed
]

Classification

The genus

Polytrichastrum was separated from Polytrichum in 1971 based on the structure of the peristome (which controls spore release).[4][5] However, molecular and morphological data from 2010 support moving some species back into Polytrichum.[4][6]

Species

References

  1. ^ Smith Merrill, Gary L. (2007), "Polytrichum", Flora of North America, vol. 27, Oxford University Press
  2. ISBN 0-231-04516-6
  3. ^ a b Silverside, A.J. (2005), Biodiversity Reference: Polytrichum commune Hedw., University of Paisley, archived from the original on 2005-12-28, retrieved 2008-02-16
  4. ^
    PMID 21622419
    .
  5. ^ 1. Polytrichastrum G. L. Smith, Flora of North America
  6. PMID 20152915
    .
  7. ^ a b c d e f g h i Polytrichum, USDA PLANTS
  8. ^ a b c d e BLWG Verspreidingsatlas Mossen online (in Dutch)
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