A key to most of the African species of Racomitrium
Translated/Compiled by C.R. Stevenson,
Norfolk College, King's Lynn, Norfolk PE30 4DJ, UK.
De Sloover (1977) published a key
which covered three African species. Magill (1981) described
an additional two species. O'Shea (1995) lists 7 species, two
of which, viz. R. lepervanchei and R. membranaceum, appear
to be confined to the Mascarenes.
What follows is an attempt to combine the
keys and descriptions of De Sloover and Magill. It therefore includes R.
lepervanchei, which De Sloover describes and illustrates. Not having
access to either a description or illustration of R. membranaceum,
it has been omitted. The description of R. crispipilum has been
taken from Sharp, Crum and Eckel (1994).
| 1 |
Plants with no hair points, or hair
points rare |
2 |
| 1* |
Plants with obvious hair points |
3 |
|
|
|
| 2 |
Plant with well developed auricles,
made up of inflated smooth walled cells which are, at first hyaline & later
brown. Leaf margin bistratose through most of its length. Lower
marginal cells sinuate. Upper leaf cells 1 - 2 (3) times as long
as wide. Leaf apex obtuse. Spores 23-32m diameter |
R. lamprocarpum (R. nigro-viride) |
| 2* |
Plants large, in dense tufts, olive
green to blackish green; saxicolous. Leaves appressed dry, recurved
wet; ovate acuminate, 3-4mm long; apex acute, rarely with short
hyaline hair point. Margins weakly recurved, entire. Lamina unistratose,
or bistratose region restricted to marginal quarter of lamina.
Lamina cells short-rectangular, incrassate, nodose. Alar cells
not forming distinct group, reddish yelow. Lower marginal cells
smooth walled, occasionally in several rows. |
R. crispulum |
|
|
|
| 3 |
Hair point strongly papillose, coarsely
and irregularly toothed, and with the apical hyaline margin decurrent
down the side of the leaf |
R. lanuginosum |
| 3* |
Not as above |
4 |
|
|
|
| 4 |
Hair point round; dentate. Hair point
not, or scarcely, twisted when dry. Leaf margin frequently sinuose
and denticulate towards the top. Leaves without hair points rare;
leaf tip acute and denticulate. Leaves scarcely decurrent; auricles
almost absent, generally not noticeable. Capsule 1.5 - 2.5 times
longer than wide. Spores 14 - 25m diameter. Internal perichaetial
leaves much shorter than vegetative leaves; very obtuse. Upper
leaf cells 2-8 times as long as wide, except sometimes at the margin |
R. lepervanchei |
| 4* |
Hair points flat |
4 |
|
|
|
| 5 |
Plants yellowish green, blackish and
dull when older. Stems sometimes short, relatively soft and supple & with
few branches; more frequently long (10cm +), stiff and fairly brittle,
with sometimes numerous short lateral branches giving an almost
pinnate appearance. Leaves (2.8) 3 - 4 (4.5) x 0.6 - 0.7 (0.9)mm,
narrowly lanceolate at the base & progressively narrower higher
up; keeled; frequently secund. Margin multistratose only in places;
revolute on one side. Upper leaves generally having a flat hair
point, with an entire to denticulate margin, which is often twisted
when dry. Leaves without hair point frequent, with an entire rounded
tip. Leaves often decurrent, with golden yellow - orange auricles
which are sometimes well marked. Perichaetial leaves large, very
sheathing, obtuse - acute. Upper leaf cells 2-8 times as long as
wide, except sometimes at the margin |
R. subsecundum (R. alare) |
| 5* |
Plants yellow-brown, often hoary.
Stems with an abundance of short tuftlike branches. Leaves erect
when dry, erect-spreading when moist, about 3-3.5mm long (including
hair points), lanceolate-acuminate, and ending in a long, crisped,
smooth, hyaline hair point. [Sometimes this is considerably reduced];
margins unistratose, recurved on one or both sides; costa shortly
excurrent into the hair point; cells linear and nodose throughout,
smooth; basal marginal cells short in 1-5 rows. Seta about 7-10mm
long; capsules about 2.5mm long, cylindric. Spores 9-12m, smooth |
R. crispipilum |
References:
De Sloover, JL. (1977) Note de bryologie
africaine IX Andreaea, Racomitrium, Gymnostomiella, Thuidium. Bull.
Jard. Bot. Nat. Belg. 47: 155-181
Magill, RE. (1981) Flora of Southern Africa. Bryophyta. Fasc.1
Sphagnaceae - Grimmiaceae. Pretoria.
O'Shea, B. (1995) Checklist of the mosses of sub-Saharan Africa. Tropical
Bryology 10: 91-198
ed.Sharp, AJ, Crum, H & Eckel, PM. (1994) The Moss flora of Mexico. Mem.
New York Bot. Garden 69. New York.
TBG38/racom Issue 1 - 15.08.96
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