GBA onlinePOLYTRICHACEAE(F. Müller) Plants small to very large and robust. Stems erect, solitary or with a few branches, arising from rhizoidal or persistent protonemal mats or from subterranean rhizomes; well-developed internal conducting systems present (hydroids for water conduction, leptoids for assimilate conduction). Leaves lower down the stem scale-like, upper leaves oblong- to lingulate-lanceolate or differentiated with a narrow to broad lanceolate limb from a clasping sheathing base that is broadly oblong to obovate-oblong, leaves mostly of rather opaque appearance and a stiff texture; whole or part of the upper surface of the limb covered by longitudinal, ribbon-like, photosynthetic lamellae, in continuous or discontinuous rows over the costa, few to several cells high, terminal lamella cells variously shaped, rounded, truncate, U-shaped or pyriform, smooth or papillose; margins plane, erect, incurved or folded, sometimes limbate, often serrate to spinose, teeth single or double; costa single, usually strong, narrow to nearly the width of the limb, percurrent to somewhat long excurrent, often with teeth on abaxial side; sheathing base cells mostly elongate-rectangular to linear; limb cells isodiametric, thick-walled. Dioicous, rarely autoicous. Perigonia often conspicuous and in the form of apical, flower-like rosettes. Perichaetia terminal; leaves differentiated. Seta elongate, stout and wiry. Capsule large, suberect to inclined, urn obtusely or sharply angled or cylindric; apophysis indistinct or distinct; stomata present or absent. Operculum usually long rostrate, oblique. Peristome single, of 32 or 64 short and rigid teeth, joined terminally onto a membranous epiphragm covering the mouth of the capsule like the head of a drum. Calyptra cucullate, usually densely hairy, less commonly smooth to slightly scabrous distally. Spores variously ornamented. Discussion.
The Polytrichaceae contain about 18 genera and some 160 or more species
with a worldwide distribution (Hyvönen et al., 1998); in sub-Saharan
Africa there are 5 genera and about 20 to 30 species. The family
is distinguished by the usual presence of longitudinal lamellae on
the upper leaf surface, the formation of an epiphragm from the columella,
and the multicellular peristome appearing single and commonly with
32 or 64 teeth. Plant size is remarkably variable. Our species can
range from 0.5 to 30 cm or more in height, mostly growing on soil
or humus, rarely on rock. Many members of this family are some of
the earliest colonizers of disturbed sites such as landslides, exposed
banks and road and trail cuts. Literature. De Sloover, J.L. 1986. Note de bryologie africaine XIII. Polytrichaceae. Bulletin du Jardin Botanique National de Belgique 56: 241-300 [keys to species, illustrations, distribution maps of selected species]. Hyvönen, J., Hedderson, T.A., Smith Merrill, G.L., Gibbings, J.G. & Koskinen, S. 1998. On the phylogeny of the Polytrichales. Bryologist 101(4): 489-504 [discussion of phylogeny of family based on morphological and molecular data]. Smith, G.L. 1971. A conspectus of the genera of Polytrichaceae. Memoirs of the New York Botanical Garden 21: 1-83 [keys to genera, limited illustrations, no generic descriptions].
One species in the area, A. androgynum (Müll.Hal.) A.Jaeger, which also occurs in central and southern America, and Australasia; about 20 species worldwide of mainly temperate regions, particularly the Northern Hemisphere.
Three species in Africa; about 25 species worldwide. Two of the African species are restricted to the southernmost part of Africa (South Africa, Lesotho). The third taxon, O. cavallii (Negri) G.L.Sm., is known from the East African mountains (Kenya, Rwanda, Tanzania, Uganda, DR Congo).
Habitat. On acid, mineral soils, in exposed sites usually associated with other tufted bryophytes; e.g. along trails, on slopes, humid rocks. Montane to alpine, 1200-4200 m. Discussion. The genus is characterized by the presence of few (< 10) sinuose lamellae, the additional production of lamellae on the dorsal leaf surface, ovoid-cylindrical, only an indistinctly angled capsule with stomata and without an apophysis, peristome teeth 32, sparsely hairy or smooth calyptra. Literature. De Sloover, J.L. 1979. Note de bryologie africaine X. Blindia, Pilopogon, Bryoerythrophyllum, Orthodontium, Orthostichidium, Oligotrichum. Bulletin du Jardin Botanique National Belgique 49: 393-408 [illustrations of O. cavallii]. De Sloover, J.L. 1986 (see family ref.) [key to all three species]. Ten species in Africa; about 52 species distributed worldwide, generally associated with temperate and montane regions. The largest and most diverse genus in the Polytrichaceae.
Habitat. On soil or soil covered rocks, cliffs and tree trunks, frequent on exposed landslides, road cuts, roadside and trail banks, heaths and on forest floor in rainforest; calcifuge pioneer plants; from near sea level to 4200 m. Discussion.
The genus is rather variable and necessarily defined by a combination
of characters. Three characters considered by Hyvönen
(1989) to be uniquely derived (synapomorphies) defining Pogonatum as
a monophyletic group included: exothecial cells roughened-papillose,
absence of stomata, and strongly pigmented 32 compound peristome
teeth. Sterile specimens may be difficult to place in the genus.
The worldwide treatment by Hyvönen (1989) and the regional
treatment of De Sloover (1986) are very useful for sub-Saharan
Africa. Literature. De Sloover, J.L. 1986 (see family ref.) [keys, illustrations]. Hyvönen, J. 1989. A synopsis of the genus Pogonatum (Polytrichaceae, Musci). Acta Botanica Fennica 138: 1-87 [keys, illustrations, distribution maps]. Touw, A. 1986. A revision of Pogonatum sect. Racelopus, sect. nov., including Racelopus Dozy & Molk., Pseudoracelopus Broth. and Racelopodopsis Thér. Journal of the Hattori Botanical Laboratory 60: 1-33 [keys, illustrations]. One species in Africa, P. formosum (Hedw.) G.L.Sm.; a genus of about 10 or more species of cool temperate regions. The records of P. alpinum (Hedw.) G.L.Sm. for the area are based on misidentifications of Pogonatum urnigerum (De Sloover, 1986). Plants medium sized to rather large, forming loose tufts or patches, dull to dark green. Stems 4-20 cm tall, erect to erect-spreading, somewhat stiff; central strand well developed. Leaves when dry erect-flexuose, appressed to spreading above base, when wet erecto-patent, spreading to recurved, strongly differentiated between sheathing base and limb, base ovate to ovate-oblong, 1.6-3 mm long, to 2.6 mm wide, limb narrowly lanceolate, 2.6-12 mm long, apex acuminate; margins plane or erect, base entire, limb sharply toothed; costa percurrent; limb cells mostly quadrate, thick-walled; cells between junction of limb and base oblate-oval to elongate, very thick-walled; sheathing base cells long rectangular, somewhat tapering or rounded, thin-walled; lamellae covering costa and lamina, in cross-section 5-9 cells high, apical cells conic, smooth. Dioicous. Capsule indistinctly 4-angled, erect to inclined, globose to rectangular, apophysis distinct, stomata present at base. Operculum rostrate, oblique. Peristome single, teeth 64, attached to epiphragm, marginal teeth on epiphragm. Calyptra cucullate, pilose. Seta flexuose. Habitat. On acidic soil and soil covered rocks in heaths, woods and moorland; montane, at elevations of 500 to 2000 m. Discussion. The genus is similar to Polytrichum, sharing the differentiated limb and base, with lamellae extending over both the costa and lamina, the peristome teeth attached to an epiphragm, and the densely hairy calyptra. It differs from that genus mainly by sporophytic characters (see key to genera). The differentiation of sterile material of P. alpinum and Pogonatum urnigerum is sometimes difficult. African material of the latter has been misidentified as P. alpinum. Polytrichastrum alpinum is usually distinct from Pogonatum urnigerum by its duller green colour (vs. glaucous green colour), longer, less wide leaf blades, longer lamellae (6-9 cells vs. 5-6 cells), apical cells of the lamellae elongated (vs. rounded or elliptical), papillae of the apical cells of the lamellae elongated (vs. round papillae), distal walls of apical cells of the lamellae highly incrassate (vs. distal walls of apical cells not or only slightly incrassate). Literature. De Sloover, J.L. 1986 (see family ref.) [key, illustration]. About 9 species in Africa, probably half or fewer are valid; a widespread genus of some 50 species.
Habitat. On soil and soil covered rocks, e.g. along trails and roads, in moorlands, heaths, peat banks, on forest floor, rocks, walls etc.; mostly calcifuge; montane to afroalpine, at elevations of 400-4950 m. Discussion. The genus is characterized by the differentiated limb and base, lamellae extending over the costa and lamina, U- or pear-shaped terminal cells of lamellae, strongly 4-angled capsules, strongly constricted hypophysis below neck, 64 peristome teeth attached to an epiphragm, lower margin of epiphragm divided into lobes alternating with peristome teeth, and densely hairy calyptra. Of the four commoner species in Africa, Polytrichum subpilosum P.Beauv. is endemic to Africa, but the other three (P. commune L. ex Hedw., P. juniperinum Willd. ex Hedw. and P. piliferum Schreb. ex Hedw.) are found almost worldwide. Literature. De
Sloover, J.L. 1986 (see family ref.) [key to the 4 commoner
species]. Click here for pdf file accepted 25.08.2000 |
Plants medium
sized, forming loose tufts, dark green to blackish-green or
-brown. Stems erect, simple to branched, radiculose,
up to 8 cm tall; central strand well-developed; rhizoids reddish-brown
or pale white. Leaves erect spreading when
wet, translucent, strongly crisped when dry, narrowly- to oblong-lanceolate,
5-10 mm long, often weakly to strongly undulate, usually toothed
on back of lamina and costa, apex acute to short acuminate,
base little differentiated, weakly sheathing; margins plane,
limbate, double-toothed; costa narrow, percurrent, in cross-section
with stereid bands above and below guide cells; laminal cells
oblong-short rectangular to subquadrate, thick-walled, unistratose;
basal cells rectangular, thick-walled; margins cells elongate,
forming 1-3-stratose border; lamellae few (4-6), confined to
upper surface of costa, 2-6 cells high, terminal cell rounded. Autoicous. Perichaetia terminal;
leaves differentiated. Seta elongate, smooth. Capsule suberect
to inclined, very long and narrow, urn cylindrical, asymmetric,
slightly to somewhat strongly curved; exothecial cells rectangular,
thick-walled. Operculum conic long-rostrate,
oblique. Peristome teeth 32. Calyptra cucullate,
glabrous, roughened at apex. Spores papillose.
Plants small,
forming low tufts, dark green to reddish-brown. Stems erect,
to 1 cm tall. Leaves somewhat crispate when dry,
erect when wet, upper leaves obovate-lanceolate, 4-5 mm long, to
2 mm wide, lower leaves oblong or obovate-oblong, apex acute, base
weakly sheathing stems; margins plane to distally incurved at apex,
denticulate in distal half; costa rather strong, percurrent; median
cells isodiametric, rather collenchymatous; basal cells short to
rather long rectangular-rounded, somewhat lax; upper marginal cells
firm, thick-walled; lower 1/3-1/2 of leaf with cells short to long
rectangular, thick-walled; lamellae in 6-7 rows, 3-6 cells high,
sinuose, terminal cell rounded. Dioicous. Perichaetia terminal;
leaves strongly enveloping seta, longer than stem leaves. Seta elongate,
to 40 mm long, slender, smooth. Capsule suberect,
ovoid-cylindrical, to 4 mm long, indistinctly 6-8 angled, apophysis
lacking; stomata present at base, superficial. Operculum conic-long
rostrate, oblique. Peristome teeth 32. Calyptra cucullate,
sparsely hairy or smooth, slightly roughed at apex.
Plants small
(a few mm) to large (up to 20 cms), solitary or forming tufts,
dark green to reddish-brown or blackish, protonema often persistent. Stems mostly
erect, simple or with few branches, occasionally distally curved. Leaves rather
crowded, contorted or crispate when dry, mostly weakly differentiated
between sheath and limb, base slightly expanded and slightly
sheathing, ovate to short oblong, limb oblong- to lingulate-lanceolate;
margins plane, dentate to somewhat sharply serrate; costa weak
to mostly strong, percurrent or excurrent, often toothed on the
abaxial side towards the apex; median cells isodiametric, thick-walled;
lamellae usually well developed, at least in the upper part of
the limb, usually covering most of the leaf surface but occasionally
few and confined to the leaf midline (e.g. P. proliferum [Griff.]
Mitt.) or absent (P. marginatum Mitt.), (1-)2-6 cells
high, terminal cells rounded, rarely truncate or pear-shaped,
smooth or rarely papillose. Dioicous. Perichaetia terminal. Seta elongate,
stout and smooth (rarely tuberculate-papillose). Capsule suberect
to inclined, urn short to long cylindrical, terete, not angular, ± symmetrical,
without apophysis or stomata. Operculum conic-mammillate. Peristome teeth
32. Calyptra densely hairy. Spores variously
ornamented.
Plants variable
in size, mostly medium sized to large and robust, gregarious
or forming compact tufts, dark to glaucous green, seldom reddish-brown. Stems erect,
rigid, simple, reddish-brown; shoots arising from underground
rhizome-like stem; central strand well developed. Leaves erect-appressed
to -spreading when dry, erect- to wide-spreading when wet, leaf
differentiated between sheathing base and limb, base ovate-oblong
and sheathing, limb oblong-, ligulate- or linear-lanceolate,
apex broadly acute to acuminate; margins of limb erect to broadly
folded and forming a flap covering adaxial surface of limb, base
entire, limb entire with apices toothed or limb sharply serrate;
costa ± narrow in leaf base, expanding in limb to 2/3-4/5
of width, percurrent to excurrent, often toothed distally on
back, in cross-section stereids above and guide cells below;
cells at transition between limb and base oblong-oblate, compressed
and thick-walled, base cells long rectangular, thin-walled; ventral
leaf surface usually covered nearly completely by lamellae, lamellae
straight, 5-8 cells high, terminal cell rounded, pear- or U-shaped,
smooth. Dioicous. Perigonia terminal,
usually conspicuous and flowerlike or cupulate; leaves strongly
differentiated, short and broadly oval to ovate. Perichaetia terminal;
leaves similar to stem leaves. Seta elongate,
erect or weakly flexuose, rather stout. Capsule suberect
to horizontal, urn somewhat longer than wide, strongly 4-angled;
neck short and compressed, constricted below urn base; apophysis
and stomata present at base of capsule. Operculum rostrate
from a plano-convex base. Peristome single,
teeth 64, teeth attached to a thick oval epiphragm, teeth alternating
with short segments or lobes beneath epiphragm. Calyptra cucullate,
densely hairy, covering capsule. Spores appearing
smooth.