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BFNA
Title: Microbryum |
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Edit level R Brum+ MICROBRYUM - POTTIACEAE XX. MICROBRYUM Schimper, Syn. 10. 1860 * [Greek mikros, small, and bryon, a moss] Richard H. Zander Pottia subg. Pottiella (Limpricht) Brotherus; Pottia sect. Pottiella (Limpricht) Nyholm; Phascum subg. Microbryum (Schimper) Limpricht; Phascum subg. Pottiella Limpricht; Phascum sect. Microbryum (Schimper) Podpěra; Phascum sect. Pottiella (Limpricht) Paris Plants in a low turf, scattered or gregarious, occasionally bulbiform, reddish brown distally, brown proximally. Stem very short, 0.2--0.4 mm, hyalodermis absent, sclerodermis absent or weakly differentiated, central strand present or absent; axillary hairs of 3--6 cells, the proximal 1-2 cells usually with thicker walls. Leaves appressed when dry, weakly spreading, tips occasionally reflexed when moist, lanceolate, elliptical or ovate, adaxial surface weakly concave to broadly channeled, short, 0.6--1.8 mm; base not differentiated, proximal margins not differentiated; distal margins recurved at midleaf and commonly recurved to near apex, entire or rarely serrulate near apex, margins occasionally less papillose and somewhat thicker walled than medially; apex broadly acute; costa excurrent as an apiculus, mucro or short awn, occasionally only percurrent, adaxial outgrowths occasionally present as a pad of enlarged parenchymatous cells, adaxial cells quadrate or short-rectangular or elongate, in 2(4--6) rows; transverse section usually round, adaxial epidermis present, adaxial stereid band absent, guide cells 2(--4) in 1 layer, hydroid strand present, occasionally central, abaxial stereid band present, round to semicircular in sectional shape, abaxial epidermis present; proximal cells differentiated across leaf or higher medially, rectangular, 2--4:1, walls of proximal cells usually thin; distal medial cells quadrate to hexagonal or short-rectangular, occasionally rhomboidal, small to somewhat enlarged, 11--15 µm wide, 1--2:1, 1-stratose; papillae usually simple (seldom 2-fid), hollow, 1--6 per lumen, occasionally branching and tall, cell-walls thin to moderately and evenly thickened, convex on both sides. Specialized asexual reproduction absent. Sexual condition monoicous, usually paroicous, occasionally synoicous. Perichaetia terminal, interior leaves often somewhat enlarged, otherwise little differentiated. Seta very short to elongate (to 4 mm). Capsule stegocarpous or cleistocarpous, theca ovate to short elliptical, apiculate when cleistocarpous, 0.5--1.1 mm, annulus absent or of 1--2 rows of weakly vesiculose cells, persistent; operculum when differentiated low-conic, peristome teeth when present 16, irregular, often rudimentary, ligulate to triangular in shape, untwisted. Calyptra conic-cucullate, occasionally mitrate. Spores large, 20--30 µm. KOH laminal color reaction red. Species 13 (4 in the flora): temperate zones worldwide. This genus is similar to Syntrichia in its broad leaves, single stereid band, and red reaction of the lamina to KOH, but differs in the short stems, distinctive reduction series involving the sporophyte, round to semicircular costal stereid band (reniform in Syntrichia), peristomes (when present) of 16 irregular, often rudimentary, truncate peristome teeth that are large in comparison with the size of the capsule, and operculum (when present) low-conic. Adaxial costal pads of cells are occasionally present (in M. vlassovii). Distinguishing features include variation in ornamentation and size of the spores, and collections of these monoicous taxa usually include sporophytes. SELECTED REFERENCES Chamberlain, D. P. 1969. New combinations in Pottia starckeana. Notes Roy. Bot. Gard. Edinburgh 29: 403--404. Chamberlain, D. P. 1978. Pottia. In: A. J. E. Smith. The Moss Flora of Britain and Ireland, pp. 234--242. Zander, R. H. 1993. Genera of the Pottiaceae: Mosses of Harsh Environments. Bull. Buffalo Soc. Nat. Sci. 32: i-vi + 1--378. 1. Distal laminal cells bulging very strongly medially, projecting as "bottle-shaped" cells on the adaxial surface of the costa 4. Microbryum vlassovii 1. Distal laminal cells weakly convex adaxially, not of distinctive shape. 2. Seta very short, capsules
nearly spherical cleistocarpous 3.
Microbryum floerkeanum 2. Seta elongate, capsules elliptical to cylindrical stegocarpous (occasionally operculum not dehiscent) or rarely cleistocarpous. 3. Spores smooth or tuberculate
(seldom also weakly papillose), 22--30 µm, 1.
Microbryum starckeanum 3. Spores papillose or spiculose, 28--39 µm. 2. Microbryum davallianum 1. Microbryum starckeanum (Hedwig) R. H. Zander, Bull. Buffalo Soc. Nat. Sci. 32: 240. 1993 Weissia starckeana Hedwig, Sp. Musc. 65. 1801; Pottia arizonica Wareham; Pottia starckeana (Hedwig) J. K. A. Müller Distal laminal cells weakly convex superficially, adaxial surface of the costa not mamillose. Seta elongate. Capsule stegocarpous or occasionally cleistocarpous, cylindrical. Spores smooth or tuberculate (seldom also weakly papillose), 22--30 µm. Varieties 6 (3 in the flora): North Temperate Zone, disjunct to austral areas. 1. Capsules cleistocarpous (seldom operculum weakly
differentiated but not dehiscent), spores both tuberculate and papillose,
occasionally nearly smooth. 1c. Microbryum
starckeanum var. fosbergii 1. Capsules stegocarpous, spores smooth or tuberculate. 2. Peristome present, usually well-developed but truncate apically, leaves stoutly mucronate to short-awned. 1b. Microbryum starckeanum var. starckeanum 2. Peristome absent or rudimentary, leaves very shortly mucronate. 1c. Microbryum starckeanum var. brachyodus 1a. Microbryum starckeanum (Hedwig) R. H. Zander var. starckeanum Stem leaves mucronate to short-awned. Capsule stegocarpous, peristome present, usually well-developed but truncate apically. Spores smooth or tuberculate. Capsules mature winter (Jan.--Feb.). Bare soil, fields; low elevations; Ariz., Calif.; Mexico (Baja California); Europe; n Africa; Pacific Islands (New Zealand). A collection from California (Pasadena, "g. 9", US) has three variants, including var. starckeanum, var. fosbergii, and what is probably best called var. starckeanum but which has an indehiscent operculum, even upon heating in KOH and Pohlstoffe. Another, from Arizona (Pima Co., Musci. Acroc. Bor.-Amer. 572, Bartram 990, US) includes var. starckeanum, var. brachyodus, and the indehiscent variant of var. starckeanum. Collections with capsules toward the large end of the size scale, previously called Pottia arizonica, often have entirely smooth spores; commonly, however, some tuberculate characteristic of M. starckeanum can be identified in at least some capsules. Also, Chamberlain (1978) described M .starckeanum (as Pottia starckeana) as having smooth or tuberculate spores in his treatment for the British Isles. Capsule contents not differentiating into spores is not uncommon in variants of M. starckeanum indicating the possibility of occasional hybridization. 1b. Microbryum starckeanum var. brachyodus (Bruch & Schimper) R. H. Zander, Bull. Buffalo Soc. Nat. Sci. 32: 240. 1993 Anacalypta starckeana var. brachyodus Bruch & Schimper in Bruch, Schimper & W. Gümbel, Bryol. Eur. : 47 (fasc. 18--20 Monogr. 6). 1843; Pottia arizonica var. mucronulata Wareham; Pottia starckeana var. brachyodus (Bruch & Schimper) J. K. A. Müller Stem leaves very shortly mucronate. Capsule stegocarpous, peristome absent or rudimentary. Spores smooth or tuberculate. Capsules mature late winter or early spring (Jan.--Mar.). Soil; 0--700 m; Ariz., Calif.; sw Asia; n Africa. Microbryum starckeanum var. brachyodus has a rudimentary peristome (as an irregular proximal membrane) or the peristome absent. The capsule mouth is commonly oblique and constricted when dry, and the costa is only shortly excurrent as a mucro (M. starckeanum var. starckeanum has short awns). 1c. Microbryum starckeanum var. fosbergii (Bartram) R. H. Zander, Bull. Buffalo Soc. Nat. Sci. 32: 240. 1993 Pottia fosbergii Bartram, Bryologist 33: 18. 1930; Phascum fosbergii (Bartram) J. Guerra Stem leaves mucronate to short-awned. Capsule cleistocarpous, peristome rarely differentiated internally, operculum absent or occasionally weakly differentiated. Spores both tuberculate and papillose, occasionally nearly smooth. Capsules mature in earl spring (Mar.). Soil; low to moderate elev.; Calif.; Mexico (Baja California). Microbryum starckeanum var. fosbergii has elliptical capsules that lack both a differentiated operculum and a peristome (except California: Ikenberry, CANM, which has a weakly differentiated operculum and rudimentary peristome teeth). This variety apparently has spores that are both tuberculate and papillose (also true in the type), occasionally nearly smooth. If the spores are unreduced (though there is no evidence they are), then hybridization would be implicated. Ros et al. (1994) have described from Spain a putative hybrid between M. starckeanum and Tortula protobryoides (as Pottia bryoides), which is evidently much the same as the var. fosbergii The var. fosbergii is known only from California and Mexico: Baja California. 2. Microbryum davallianum (Smith) R. H. Zander, Bull. Buffalo Soc. Nat. Sci. 32: 240. 1993 Gymnostomum davallianum Smith, Ann. Bot. 1: 577. 1805; Pottia davalliana (Smith) C. Jensen; Pottia starckeana subsp. minutulum (Schwägrichen) D. F. Chamberlain Distal laminal cells weakly convex superficially, adaxial surface of costa not mamillose. Seta elongate. Capsule cylindrical, stegocarpous but never cleistocarpous. Spores granulose, low-papillose or spiculose, large, 28--39 µm. Varieties 3 (3 in range of the flora): North America; Mexico; Europe; sw Asia; Africa; Pacific Islands (New Zealand). 1. Capsules commonly wide-mouthed when dehisced, with a single row of thickened cells below mouth, peristome absent, spores spiculose, 31--39 µm. 2a. Microbryum davallianum var. davallianum 1. Capsules narrow mouthed when dehisced, with usually 2 or more rows of thickened cells below mouth, peristome variously absent or present, spores merely papillose, 27--34 µm. 2. Peristome rudimentary or absent. 2c. Microbryum davallianum var. conicum 2. Peristome well developed. 2b. Microbryum davallianum var. commutatatum 2a. Microbryum davallianum (Smith) R. H. Zander var. davallianum Capsule commonly wide-mouthed when dehisced, with a single row of thickened cells below mouth; peristome absent. Spores spiculose (finely spinose) and large (31--39 µm.). Capsules mature late summer to early winter (Sept.--Nov.). Bare soil, vacant lots, fields; low to moderate elevations; Ont.; Mich., N.Y.; Europe; sw Asia; n Africa; Pacific Islands (New Zealand). The spines of the spores are 2.0--2.5 µm. Distal laminal papillae are hollow or occasionally solid, ca. 2 per lumen, usually simple but in some specimens (e.g. Ontario, Bruce Co., C. Williams 1200, CANM) mostly bifid and hollow (with a distinct saddle between the projections) and distinctly cee-shaped in optical section. 2b. Microbryum davallianum var. commutatum (Limpricht) R. H. Zander, Bull. Buffalo Soc. Nat. Sci. 32: 240. 1993 Pottia commutata Limpricht, Laubm. Deutschl. 1: 537. 1888; Pottia davalliana subsp. commutata (Limpricht) Podpěra Capsule narrow-mouthed when dehisced, with usually 2 or more rows of thickened cells below mouth; peristome well developed though apically truncate. Spores papillose, 27--34 µm. Capsules mature late winter (Feb.). Soil; low elevation; Calif.; Europe; sw Asia; n Africa. The var. commutatum is known only from California (Berkeley, Howe 79, US), last collected in 1894, from which station it is disjunct to the Old World. 2c. Microbryum davallianum var. conicum (Schwägrichen) R. H. Zander, Bull. Buffalo Soc. Nat. Sci. 32: 240. 1993 Gymnostomum conicum Schwägrichen, Sp. Musc. Suppl. 1(1): 25. 1811; Pottia starckeana ssp. conica (Schwägrichen) D. F. Chamberlain; Pottia texana Wareham Capsule narrow-mouthed when dehisced, with usually 2 or more rows of thickened cells below mouth; peristome rudimentary or absent. Spores papillose, 27--34 µm. Capsules mature late winter and spring (Feb --Apr ). Soil; low elevations; Calif., Nebr., Okla., Tex.; Mexico (Baja California); Europe; sw Asia; w and s Africa; Pacific Islands (New Zealand). The San Marcos, Texas specimen (MICH) of the var. conica has a flaring mouth like M. davallianum var. davallianum. Another Texas specimen (Orcutt 5565, CANM, WTU) has a weak peristome (a thin line of proximal membrane). 3. Microbryum floerkeanum (Weber & Mohr) Schimper, Syn. 11. 1860 Phascum floerkeanum Weber & Mohr, Bot. Taschenb. 70, 45. 1807 Distal laminal cells weakly convex superficially, adaxial surface of costa not mamillose. Seta extremely short, nearly absent. Capsule nearly spherical, cleistocarpous. Spores papillose, 20--25 µm. Capsules mature in late fall (Nov.--Oct.) Soil, fields, pastures; low elevations; Ont.; Europe, sw Asia; n Africa. The leaves are ovate to ovate-lanceolate and sheath the immersed capsule. The papillae occur near the apex of the leaf, one per lumen, and are large, nearly covering the lumen. The calyptra is variably papillose, merely rough, or smooth. A poorly distinguishable variety, var. badium (BSG) Schimp., may be segregated by its long-acuminate leaf apices---the typical variety has short-acuminate apices. 4. Microbryum vlassovii (Lazarenko) R. H. Zander, Bull. Buffalo Soc. Nat. Sci. 32: 240. 1993 Phascum vlassovii Lazarenko, J. Inst. Bot. Ac. Sc. R.S.S. Ukraine 26--27: 196. 1938 Distal laminal cells strongly bulging superficially in medial portion of leaf, adaxial surface of costa strongly mamillose, beset with "bottle-shaped" cells. Seta short, nearly absent. Capsule nearly spherical apiculate, cleistocarpous. Spores papillose, ca. 18--24 µm. Substrate and elevational range unknown; B.C.; Calif.; Asia. Sporophytes were immature in the area of the flora. This distinctive species was reported from British Columbia by T. T. McIntosh (1989) and Spain by M. N. Jiménez et al. (1990), otherwise known from Armenia, central Asia and the Ukraine. The long, smooth cell making up the end of the mucro is reminiscent of that of Chenia. The rhizoids bear distinctive unicellular hemispherical excrescences that may serve as tubers. Tortula acaulon may have ampullose adaxial costal cells (T. L. Blockeel 1995), but is yellow in KOH. OTHER REFERENCES Blockeel, T. L. 1995. A note on Phascum cuspidatum ssp. papillosum in the British Isles. Bull. British Bryol. Soc. 65: 59--60. Jiménez M. N., R. M. Ros and J.Guerra. 1990. Phascum vlassovii Laz. (Pottiaceae, Musci) en Europa. Anales Jard. Bot. Madrid 47: 234--235. McIntosh, T. T. 1989. Bryophyte records from the semiarid steppe of northwestern North America, including four species new to North America. Bryologist 92: 356--362. Ros, R. M., J. Guerra and M. J. Cano. 1994. Pottia ×andalusica (Musci: Pottiaceae), un híbrido interespecífico en Pottieae. Cryptogamie, Bryol. Lichénol. 15: 199--204.
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