Other acrocarps

(If you need to know what an Acrocarp is, click here)

On rocks (including surfaces of boulders, walls and rock clefts where only negligible amount of soil has accumulated).

On soil (including gravelly detritus, sand, clay, loam, peaty humus, etc. N.B. Plants of soil-capped walls and on thin soil covering roadside or pathway should be sought in this subsection).

On wood —trees, logs, wooden stakes or decaying tree-stumps.


1 Stems prostrate or ascending, with irregular tufts of short branches — 2

Stems erect or nearly so, unbranched or with forked branching — 4

2 Leaf apex obtuse; dark green plant growing in or near water of streams or lakes — Rhacomitrium aciculare

Leaf apex acute, yellowish green or blackish olive plants; not semi-aquatic; common on exposed boulders on mountains — 3

3 Plant deep olive-green to nearly black; usually in rather close cushions (forms of) — Rhacomitrium heterostichum (N.B. Andreaea is distinct in very small size and forked branching.)

Plant light yellowish green to tawny; usually in ill-defined mats — R. fasciculare

4  Minute plants (only a few millimetres tall including seta and capsule); soon chalk cliffs — Seligeria calcarea

Plants taller; habitat different — 5

5 Leaves 0.5-1 mm.; dark red-brown to blackish plants on siliceous rocks at high altitudes; capsule opening by slits — Andreaea spp. (N.B. A plant with stems 1-2 cm. tall, leaves 0.5 mm. long and red-brown colour well marked, will probably be A. rupestris; smaller, blacker, slightly longer-leaved plants will probably be A. rothii.)

Leaves usually larger; if leaves only 0.5-1 mm., plant never as above in colour, habitat and capsules — 6

6 Leafy shoots with bright metallic gloss — Bryum alpinum

No metallic gloss — 7

7 Strictly maritime, within reach of spray (chiefly on west coast); dark brown to black below, yellow-green at tips of shoots, which form characteristic twisted points when dry; capsule immersed — Grimmia maritima

Habitat and sum of characters not as above — 8

8 Leaves very short (about 1 mm.) — 9

Leaves longer (mostly 2 mm. or over) — 12

9 Forming deep cushions (2-6 cm. or more deep) in mountain rock clefts — 10

Forming smaller cushions (usually 1-2 cm. deep) in lowland habitats — 11

10 Tips of shoots vivid green; bases of stems often matted together with red-brown tomentum — Anoectangium compactum

Tips dull green; bases of stems dull brown and not tomentose — Gymnostomum aeruginosm

11 Cushions vivid light green; leaves curled and twisted when dry; each leaf several times as long as broad (very common plant) — Barbula convoluta

Cushions usually mid-green; leaves straight and appressed when dry; each leaf concave, broad (only about twice as long as broad) — B. trifaria

12 Capsules present, each completely covered by very conspicuous (pale and shining), long, narrow calyptra — Encalypta vulgaris

Capsules, if present, not having calyptra of this type — 13

13 Leaves appressed to stems and scarcely twisted when dry; capsule immersed or on very short seta (just clear of leaves) — 14

Leaves much twisted and curled when dry; capsule on long seta — 15 (N.B. A plant with appressed leaves when dry, a long seta and pendulous capsule, will probably be Bryum sp.)

14 Shoots narrow and slender, pointed when dry; capsule immersed; calyptra not conspicuous, lid and peristome bright red — Grimmia apocarpa

 Shoots stout, with crowded leaves, blunt-tipped when dry; capsule raised just clear of leaves, its most noticeable feature the bell-shaped pale yellowish, slightly hairy calyptra — Orthotrichum anomalum var. saxatile

15 Base of plant strongly tinged with red-brown — Barbula recurvirostra

Base of plant dull brown to blackish —16

16 Leaves long, fully 3 mm. — 17

Leaves shorter; 1.5-2 mm. — 18 (N.B. A plant with short lower leaves and longer (up to 2.5 mm.), broad upper leaves crowded together in a terminal tuft and spirally twisted corkscrew-wise when dry will probably be Bryum capillare.)

17 Plant yellowish or olive-green above, black below; capsules usually plentiful; on siliceous rocks — Ptychomitrium polyphyllum

Plant light green above, light brown below; almost always sterile; on calcareous rocks — Tortella tortuosa

18 Forming deep dense cushions (stems commonly 3-7 cm.) on wet rock ledges and in rock clefts in mountain districts — Amphidium mougeotii

Small cushions, with shorter stems; habitats various — Barbula spp., Trichostomum spp., etc.

(if you get to here and the species has not keyed out, it probably requires microscopic determination)


1 Minute plants {1 cm. or less including seta and capsule), on bare patches of soil in fallow fields, gardens, etc. — 2

Plants mostly taller; if dwarf, then not of this habitat — 6

2  Capsule immersed among leaves — 3

Capsule raised on evident seta several millimetres in length — 4

3 Plants bud-like; leaves broad, nerved, their margins entire — Phascum cuspidatum

Plants not bud-like; leaves narrow, nerveless, their margins toothed — Ephemerum serratum

4 Leaves curved and turned to one side; seta bright red; capsule curved, semi-erect; peristome well developed (obvious under lens) — Dicranella varia

Leaves not as above; seta yellow to orange; capsule erect; peristome poorly developed or absent — 5

5 Capsule short and broad (1 mm. long), wide-mouthed and cup-like when old and empty; peristome lacking — Pallia truncata (N.B. Physcomitrium pyriforme has capsule of rather similar shape but more than twice as big; it grows on bare clay soil)

Capsule narrowly cylindrical, even when old and empty; peristome variably developed, rarely quite lacking —Weissia contra versa

6 Shoots silver-grey, narrow and catkin-like with closely appressed leaves; common moss of town roadsides — Bryum argenteum

Shoots neither silver-grey nor markedly catkin-like —7

7 Shoot tips forming minute gemma-bearing cups which are the most conspicuous feature of the plants — Tetraphis pellucida

 Gemma-bearing cups lacking — 8

8 Shoots with bright metallic gloss — Bryum alpinum

No metallic gloss — 9

9 Habitat wet detritus by mountain streams or marshy ground by bog springs — 10

 Habitats other than these — 13

10 Stems short (usually 0,5-1,5 cm.); leaves pink-tinged — Bryum pollens

Stems taller (2-10 cm.); leaves green or yellowish — 11

11 Shoots narrow; leaves small (1 mm.), appressed or nearly so except at their tips; colour usually vivid glaucous green with variable yellowish tinge — Philonotis fontana (Photo is P. marchica)

Shoots wide; leaves larger (2-3 mm.), spreading or recurved; colour never approaching vivid glaucous green — 12

12 Leaves with clasping bases, and tips which stand out at right angle with stem; colour bright yellow-green to olive; stems green — Dicranella squarrosa

Leaves straight, forming relatively narrow angle with stem; colour deep green often tinged reddish; stems red — Bryum pseudotriquetrum

13 Lower part of plant red-brown — Barbula recurvirostra = Bryoerythrophyllum recurvirostre

Red-brown colour lacking — 14

14 Leaves long, fully 3 mm.; calcicole species with leaves strongly and irregularly curled and twisted when dry — Tortella tortuosa

Leaves shorter, 2.5 mm. or less, either neatly spirally curled or only lightly twisted when dry — 15

15 Capsules pendulous; upper leaves forming more or less erect tufts at shoot tips —16

Capsules erect or nearly so; upper leaves not forming erect terminal tufts — 19

16 Plants strongly tinged salmon-pink — Bryum pollens

This colour lacking —17

17 Leaves corkscrew-curled when dry; nerve projecting from leaf tip as fine greenish hair — Bryum capillare

Leaves straight or lightly twisted when dry; greenish hair lacking — 18

18 Seta long (1.5-4 cm.); leaves lanceolate; chiefly on peaty soils — Pohlia nutans

Seta short (1-1.5 cm.); leaves ovate; chiefly on clay soils — Bryum bicolor

(N .B. Plants with long seta and ovate leaves that' key out' here will be Bryum spp. that cannot be identified by field characters alone.)

19 Each capsule completely covered by very conspicuous (pale and shining), long narrow calyptra — Encalypta vulgaris

This type of calyptra lacking — 20

20 Capsule pear-shaped — Physcomitrium pyriforme

Capsule cylindrical — 21

21 Seta yellow; plants usually vivid light green in colour — Barbula  convoluta

Seta red or purple; plants darker green — 22

22 Leaves broad-tipped; strongly spirally twisted (corkscrew- curled) when dry — Barbula unguiculata

Leaves acute-tipped; irregularly curled but not spirally twisted when dry — 23

23 Plants green (often tinged wine red), growing in wide patches; the massed setae, in spring, forming sheets of purple-red on waste land; capsules erect when young, curved and inclined when old — Ceratodon purpureus

Plants brownish or olive-green (not tinged wine red); in small patches or tufts; old capsules straight, erect — Barbula fallax (N.B. This is the commonest of several species of Barbula that might key out here.)


1 Spherical green (gemma-bearing) 'pin-heads' on evident stalks at tips of shoots —Aulacomnium androgynum

Minute green or brownish (gemma-bearing) cups at tips of shoots — Tetraphis pellucida

(Both occur on stumps in relatively late stage of decay)

Neither 'pin-heads' nor cups present at shoot tips — 2

2 Leaves corkscrew-curled when dry; nerve projecting from leaf tip as fine greenish hair; young capsules pendulous — Bryum capillare

Leaves variously twisted or nearly straight when dry (never neatly and closely corkscrew-curled); nerve not projecting from leaf-tip; young capsule erect — 3

3 Leaves very short (about 1 mm.), lightly twisted when dry, quickly becoming spreading-recurved when moistened; plant vivid green, in neat compact patches; almost always barren —Zygodon viridissimus

Leaves longer (about 2 mm.); various when dry but not recurved when moist; plant dark green or olive; commonly fertile — 4

4 Capsule smooth, on seta 8-20 mm. long; calyptra glabrous and inconspicuous — 5

Capsule furrowed, on much shorter seta; calyptra hairy and conspicuous — 6

5  Seta yellow, 5-10 mm. Long — Dicranoweissia cirrata

Seta shining purple-red, often much longer — Ceratodon purpureus

6 Leaves appressed to stem and only very lightly twisted when dry, deep green; calyptra sparsely hairy — Orthotrichum affine (This is the commonest of a number of species of Orthotrichum that occur on trees.)

Leaves much curled and twisted when dry, usually olive-green; calyptra densely hairy — Ulota crispa (The commonest of several Ulota spp. that occur on trees.)

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