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Portrait of Common haircap

Nature · Ferns, grasses & other plants

Common haircap

Native moss · shoots up to 40 cm, usually about 20 cm · bogs, wet heath and damp acid woodland

Polytrichum commune — Polytrichaceae

Common haircap is one of the largest mosses in Britain, forming spiky green hummocks and turfs on wet acid ground, from moorland flushes and bog edges to damp woodland. It is a moss, not a flowering plant: it has no flowers, seeds or true roots, and its spore capsules ride on reddish stalks above the leafy shoots. The 'haircap' is the hairy hood that covers each young capsule.

How to spot them

  • ▸Tall, stiff, unbranched shoots up to 40 cm (usually about 20 cm) forming star-like rosettes of leaves when wet
  • ▸When dry the leaves are strongly inrolled and twisted; when moist they spread out or curve away from the stem
  • ▸Four-angled, box-like capsule on a reddish stalk in summer, wearing a hairy golden-brown cap
  • ▸Damp, acidic, often shaded habitats: bog margins, wet heath, poor fen and wet woodland
  • ▸Look-alike: juniper haircap is much shorter, greyer and lives in dry acid places; the leaf tip needs a hand lens to confirm

How to know it

One of Britain's largest mosses, with stiff stems to 40 cm forming spiky hummocks on wet acid ground

Common haircap — a moss, not a flowering plant.

When wet its leaves splay into little stars; when dry they inroll and twist

Common haircap.

Its box-like, four-angled capsule is covered by a hairy hood that gives the group its name

Common haircap — the calyptra.

Frequent in damp, acidic shade; tolerates moderate pollution and nutrient enrichment

Common haircap — Polytrichum commune.

Its tall stems make hummocks that can spread half a metre across in wet acid hollows

Common haircap.

Quick-fire facts

  • •Mosses are not flowering plants: no flowers, no seeds, and they reproduce by spores; mosses (Bryophyta), liverworts and hornworts are the three groups of bryophytes, and none of them flowers
  • •Shoots reach up to 40 cm long, though about 20 cm is usual, according to NatureSpot
  • •Widespread and frequent in most of Britain in damp, acidic habitats
  • •The hairy calyptra that shields the young capsule gives haircap mosses their name
  • •Hummocks in favoured wet habitats can grow half a metre across, according to the British Bryological Society's account
  • •The leaves carry parallel photosynthetic lamellae on the upper surface, a more elaborate arrangement than in most mosses
  • •Sphagnum is another moss of the same wet, acid ground, but it has no such stiff upright stems

Drill it — 6 cards

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Sources