|
BFNA Title: Brachymenium |
|
XX.
BRACHYMENIUM Schwägrichen, Sp. Musc. Frond. Suppl. 2(1): 131. 1824 * [Latin brachy, short, and menium, a
membrane, alluding to poor development of endostome] John R. Spence Plants
small, forming dense turfs or cushions, green to red-green. Stems short, 0.3--1.5 cm, sometimes
rosulate, sparsely to strongly branching by subfloral innovations, rhizoids
sparse to abundant, variously colored, smooth to papillose, micronemata often
present on stems. Leaves
irregularly contorted to spirally twisted around stem when dry,
erect-spreading when wet, broadly ovate, 1--2.5 mm, smaller proximally, leaf
base not curved at insertion, not or only weakly decurrent; margins plane or
revolute proximally, 1-stratose, limbidium absent or present, distal margins
serrulate to serrate, apex acute to broadly rounded, differentiated apiculus
absent, costa shortly to moderately long-excurrent in a stout, denticulate,
colored awn, transverse section with stereid band single and well developed,
guide cells present; adaxial supracostal cells irregularly to regularly
quadrate or short-rectangular at leaf base, laminal cells heterogeneous, distal
and medial cells generally similar, short-rectangular to irregularly
hexagonal, 1.5--3(--4):1, not in rows oblique to the costa, thin- to somewhat
thick-walled, proximal cells usually quadrate, distinctly different in shape,
walls not pitted, alar cells usually similar to juxtacostal cells. Specialized asexual reproduction by
spherical rhizoidal tubers and bulbils in leaf axils. Sexual condition dioicous; perigonia and perichaetia terminal, perichaetial
leaves same size as vegetative leaves or typically larger, sometimes forming
a rosette, inner leaves highly differentiated, often narrower with a weaker
costa. Seta single, variously
colored, elongate, straight. Capsule
erect to suberect, ovate to cylindric, wrinkled when mature, hypophysis
slender to well-differentiated, often rugose, operculum short to tall-conic;
peristome double, exostome red-brown proximally, pale distally, papillose,
teeth linear-lanceolate, separated at base, endostome of basal membrane
hyaline to pale yellow, low, segments absent or short and blunt, cilia
rudimentary or absent. Spores shed
singly, 12--18 \um, smooth or papillose, pale tan to brown. Species ca. 30 (2 in the flora):
worldwide in tropical and subtropical regions, primarily Paleotropical. The genus Brachymenium was
originally based on the erect capsule with a variously reduced peristome, but
recent research indicates the genus to be highly polyphyletic. Apparently this sporophytic syndrome has
evolved independently several times in groups with distinctive
gametophytes. I have used gameophyte
morphology as the basis for re-assigning sections and species to other
genera. Typical Brachymenium consists of subtropical-tropical
epiphytes with gametophytes similar to those of Rosulabryum. Brachymenium
andersonii has been re-assigned to Rosulabryum, while the small
species B. exile Dozy & Molkenboer is now placed in Gemmabryum
near the G. bicolor complex. Brachymenium
niveum and B. systylium have been transferred to the newly erected
genus Leptostomopsis, of which the latter is the type. The only
remaining North American species, B. macrocarpum and B. mexicanum,
are probably not closely related to the type section of Brachymenium. H. Ochi
(1980) placed B. macrocaprum in sect. Peromnium, along with B.
regenellii Hampe and B. jamesonii SELECTED REFERENCES: Ochi, H.
1980. A revision of the Neotropical Bryoideae, Part 1. J. Faculty Educ.
Tottori Univ., Nat. Sci. 29: 49--154.
Spence, J. R. 2006. New combinations in the Bryaceae (Bryophyta) for 1. Leaves strongly spirally
twisted around stem when dry, limbidium present; large red spherical tubers
present in sterile material
......................................................................1. Brachymenium
macrocarpum 1. Leaves imbricate to irregularly
contorted when dry, limbidium absent; tubers lacking
....................................................................................................................2.
Brachymenium mexicanum 1. Brachymenium macrocarpum Cardot, Rev. Bryol. 38: 6. 1911 Plants small, forming dense dark green to
olive green cushions, not shiny. Stems 1--2 cm, strongly rosulate,
innovations and fertile stem leaves somewhat differentiated, leaves of
innovations smaller. Leaves
ovate, 0.6--1.5 mm, spirally twisted
around stem when dry, forming rosettes when wet, somewhat concave, margins
weakly revolute proximally, plane distally, distinctly serrate, limbidium
usually present, of 1--2 rows of somewhat elongate incrassate cells, apex
broadly rounded-acute; costa short-excurrent into a short stout somewhat
yellowish-hyaline denticulate hairpoint; distal and median laminal cells
hexagonal to short-rectangular, 20--50 x 15--20 \um, 2--3:1, proximal cells
quadrate, Specialized asexual reproduction of rhizoidal tubers,
spherical, 100--300 \um, red to orange-red, commonly on rhizoids at base of
stem. Sexual condition dioicous. Seta
1--2 cm, light brown to red-brown. Capsule
1--3 mm, elongate-ovate to subcylindric, distinctly wrinkled when dry. Capsules mature spring--summer
(Apr--Aug). Uncommon on tree trunks, wood and occasionally rock, rarely on
mineral soil; 0--1000 m; Brachymenium macrocarpum
is a distinctive species that, within its range, should be easy to identify. It
forms dense turfs or cushions on trees and rocks. The very similar B. klotzschii (Schwägrichen) 2.
Brachymenium mexicanum
Montagne, Ann. des Sci. Natur., Bot., sér. 2, 9: 54. 1838 Plants in open to dense turfs on soil or
rock, green, yellow-green, to golden, often shiny-lustrous. Stems
0.5--1(--2) cm, gemmiform to somewhat rosulate, innovations and fertile stem
leaves somewhat differentiated, leaves of innovations smaller. Leaves
1--2(--3) mm, strongly imbricate, slightly twisted when dry, concave, not
decurrent, apex acute, margins plane to weakly recurved proximally, distal margins
smooth to serrulate, limbidium absent, costa strong, short to long-excurrent
in an awn, distal and mid-laminal cells rhomboidal to elongate-hexagonal,
40--60 x 10--16 \um, mostly 3--4:1, moderately incrassate, proximal laminal
cells abruptly quadrate to short-rectangular, 1--2:1, wider and shorter than
cells above. Specialized asexual reproduction lacking. Sexuality dioicous. [Capsule
2--3(--4) mm, erect, pyriform to cylindric with somewhat thickened and rugose
apophysis; peristome double, reduced, endsotome low, segments and cilia
absent or rudimentary.] Capsules
unknown in flora region. Rare on dry rock outcrops or soil covered crevices,
1000 m; AZ; Brachymenium
mexicanum is distinguished from B. macrocarpum by the
irregularly contorted leaves, lack of a limbidium, and absence of rhizoidal
tubers. The sporophyte
description is based on Mexican material. |
