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Pottiaceae Schimp., Coroll. Bryol. Eur. 1855[1856].
丛藓科
Plants small to medium-sized, or rather large, often turf-forming or in loosely caespitose patches, dull greenish above, brownish below. Stems erect, short to elongate, simple or irregularly to compositely branching; central strand mostly developed, sometimes absent. Leaves in several rows, usually contorted, or appressed when dry, erect-spreading or squarrose-recurved when wet, often narrowly lanceolate to linear-lanceolate, or ovoid, triangular to elliptic or ligulate; apices usually gradually acuminate or abruptly acute, occasionally obtuse or rounded; bases usually narrowly ovate to oblong, sometimes sheathing; margins entire, sometimes dentate above, seldom bordered by thick-walled or elongate cells, often unistratose, sometimes multistratose, commonly recurved or incurved below, sometimes plane; costa single, well developed, percurrent to shortly excurrent or awned, occasionally ending a few cells below the apex, in cross section usually with 1 or 2 stereid bands; upper leaf cells generally small, subquadrate, quadrate or hexagonal, rarely short-rectangular, usually firm-walled or incrassate, mostly papillose or at least bulging, rarely smooth; lower cells mostly smooth, rectangular, generally thin-walled, pellucid, not differentiated at the alar regions. Brood bodies rather common. Dioicous or autoicous. Perichaetial leaves often sheathing at base. Setae generally terminal, elongate, erect, but often twisted; capsules usually erect, symmetric, ovoid to cylindric, mostly stegocarpous, rarely cleistocarpous and spherical; exothecial cells smooth; neck usually absent; opercula mostly short-conic to long-rostrate; annuli mostly in 1–2 rows of inflated cells, sometimes absent, occasionally revoluble or deciduous; peristome single, consisting of 16, erect, oblique or often spirally (clockwise) twisted teeth, occasionally absent or rudimentary, teeth entire, linear-lanceolate or deeply split into 2 filiform, striate or papillose divisions; basal membrane usually low or absent, sometimes high, trabeculate. Calyptrae smooth, usually cucullate, seldom mitrate. Spores spherical, small, usually densely papillose.
This is a very large family widely distributed in temperate regions of the world, with a small number of species and genera occurring in tropical and arctic regions. Most species of the Pottiaceae occur on calcareous habitats, especially on rocks and disturbed soil. The family includes 7 subfamilies, 6 tribes, 76 genera, and some 2000 taxa worldwide (Zander 1993). There are 36 genera known from China, which can be grouped into 5 subfamilies according to Zander’s (1993) system: Timmielloideae: upper lamina regularly bistratose (Timmiella).
Chionolomoideae: ventral stereid band larger than the dorsal one (Pseudosymblepharis).
Trichostomoideae: stem sclerodermis poorly differentiated, epidermal cells usually thin-walled in cross section (Eucladium, Pleurochaete, Tortella, Trichostomum, and Tuerckheimia).
Merceyoideae: ventral stereid band usually smaller than the dorsal one and its leaf base often differentiated into an ovate or rectangular area (Anoectangium, Barbula, Bellibarbula, Bryoerythrophyllum, Didymodon, Gymnostomiella, Gymnostomum, Gyroweisia, Hydrogonium, Hymenostylium, Leptodontium, Reimersia, Scopelophila).
Pottioideae: ventral stereid band usually absent and its leaf base little differentiated in outline (Aloina, Chenia, Crossidium, Desmatodon, Hilpertia, Hyophila, Luisierella, Molendoa, Phascum, Pottia, Pterygoneurum, Stegonia, Syntrichia, Tortula, Weisiopsis, and Weissia). Hennediella heimii (Hedw.) Zand. was reported from Xinjiang (Tan et al. 1995), but we cannot confirm this report.
P.-C. Chen (1941) provided a landmark treatment of Asiatic Pottiaceae and established the most comprehensive framework for the family classification in China. His discussions of generic relationships and his generic concepts are still well founded. He recognized six subfamilies of the Chinese Pottiaceae: Cinclidotoideae, Pottioideae, Trichostomoideae, Eucladioideae, Leptodontioideae, and Barbuloideae. His system of subfamilial classification was primarily based on such characters as capsule and costa anatomy, leaf shape and leaf margin recurvature, operculum length, differentiation of leaf bases, and morphology of the laminal papillae. The subfamilies are not dealt with by this study. In preparing the treatments of Chinese Pottiaceae, the following monographs and treatments have been very useful: X-J. Li (1981, 1985, 1996), X.-J. Li & Iwatsuki (1993, 1996, 1997), Satio (1975), Sollman (1983), and Zander (1978, 1982, 1986, 1989, 1993).
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| 1 |
Leaves usually lanceolate; margins plane to involute; costa shortly excurrent, usually with 2 stereid bands |
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(2) |
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Leaves lanceolate to ligulate or spathulate; margins plane to recurved; costa ending below the apex or long excurrent, with dorsal stereid band or 2 stereid bands |
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(7) |
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| 2 (1) |
Upper lamina bistratose medially, the cells not vertically aligned near the costa but grading to vertically evenly stacked toward the leaf margins |
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30 Timmiella |
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Upper lamina nearly always unistratose, if bistratose (rarely) then the upper cells vertically situated directly over the lower cells throughout |
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(3) |
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| 3 (2) |
Leaves long linear-lanceolate, strongly sheathing at the base; margins plane; ventral stereid band larger than the dorsal band |
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24 Pseudosymblepharis |
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Leaves lanceolate to oblong-lanceolate or oblong-ovate, not sheathing at the base; margins plane, erect, or weakly to strongly incurved or recurved; ventral stereid band smaller than the dorsal or absent |
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(4) |
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| 4 (3) |
Leaf margins distinctly involute even when moist |
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36 Weissia |
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Leaf margins plane or erect, or somewhat incurved near the apex when dry |
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(5) |
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| 5 (4) |
Basal leaf cells, if differentiated, not forming a V-shaped region across the base; peristome teeth short, erect, often bifid |
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33 Trichostomum |
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Basal leaf cells forming a V-shaped region with hyaline cells extending upward along the leaf margins; peristome teeth long, twisted |
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(6) |
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| 6 (5) |
Leaf margins coarsely dentate, upper marginal cells rectangular and clearly longer than median cells; perichaetia lateral on main axis or at ends of short lateral branches |
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22 Pleurochaete |
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Leaf margins entire, upper marginal cells not longer than median cells; perichaetia terminal on main axis |
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31 Tortella |
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| 7 (1) |
Leaves bearing lamellae or filaments on the upper dorsal surface of the costa |
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(8) |
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Leaves without lamellae or filaments on the costa |
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(10) |
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| 8 (7) |
Stem central strand absent; leaves fleshy; margins inflexed; costa percurrent or shortly excurrent, ending in a reddish awn |
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1 Aloina |
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Stem central strand present; leaves thin; margins plane or recurved; costa long-excurrent as a hyaline awn |
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(9) |
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| 9 (8) |
Leaf margins revolute; costa bearing branched filaments |
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7 Crossidium |
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Leaf margins plane; costa bearing 2-3 longitudinally inserted lamellae |
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25 Pterygoneurum |
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| 10 (7) |
Leaves usually lingulate to spathulate or broadly ovate-lanceolate; costa with dorsal stereid band only; upper leaf cells mostly larger, lax |
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(11) |
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Leaves usually lanceolate to lingulate; costa with two stereid bands; upper leaf cells mostly small |
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(22) |
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| 11 (10) |
Leaves mostly spathulate or narrowly lingulate; basal leaf cells mostly short-rectangular; upper leaf cells ventrally mammillose-bulging, dorsally weakly convex |
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(12) |
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Leaves often broadly ovate-lanceolate or narrowly spathulate; basal leaf cells usually broadly long-rectangular; upper leaf cells convex on both surfaces, smooth or papillose |
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(14) |
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| 12 (11) |
Peristome absent; leaf cells smooth, or only somewhat bulging |
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27 Scopelophila |
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Peristome present; mammillose-bulging |
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(13) |
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| 13 (12) |
Costa dorsal epidermis present; leaves linear-lingulate, with the V-shaped area of inflated hyaline cells at the base; peristome teeth 16, widely spaced |
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35 Weisiopsis |
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Costa dorsal epidermis absent; leaves narrowly spathulate, without the distinct V-shaped area at the base; peristome teeth 32, closely set |
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19 Luisierella |
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| 14 (11) |
Plants minute, usually 1.5-3.0(-5.0) mm tall; peristome absent or rudimentary |
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(15) |
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Plants usually more than 5.0 mm tall; peristome present, filaments |
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(18) |
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| 15 (14) |
Leaves acute to acuminate, mostly piliferous; capsules immersed, spherical, inoperculate |
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21 Phascum |
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Leaves apiculate to short-awned, or rounded at the apex; capsules long-exserted, cylindrical, setae elongated, operculate |
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(16) |
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| 16 (15) |
Leaf apices rounded or rounded obtuse; costa ending just above the leaf-middle |
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11 Gymnostomiella |
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Leaf apices apiculate to short-awned; costa excurrent |
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(17) |
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| 17 (16) |
Plants bud-like, silver-green; upper leaf cells rhombic, smooth; peristome rudimentary |
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28 Stegonia |
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Plants not bud-like, green; upper leaf cells quadrate or hexagonal, pluripapillose, rarely smooth; peristome absent |
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23 Pottia |
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| 18 (14) |
Leaf cells smooth, basal cells weakly differentiated from the median-cells |
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(19) |
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Leaf cells papillose, basal cells distinctly differentiated from the median-cells |
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(20) |
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| 19 (18) |
Leaf margins plane or only weakly recurved near the base; costa percurrent |
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6 Chenia |
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Leaf margins strongly revolute; costa excurrent, ending in a hyaline awn |
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14 Hilpertia |
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| 20 (18) |
Leaves not crisped or not distinctly contorted when dry; leaf cells laxer, pellucid; peristome teeth nearly erect and free |
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8 Desmatodon |
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Leaves usually contorted when dry; leaf cells firm, less pellucid; peristome teeth wound in spiral |
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(21) |
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| 21 (20) |
Plants usually larger, to 12 cm tall; leaf cells broader; costa often long-excurrent, ending in a long-hyaline awn, costa dorsal epidermis absent; peristome with a high basal membrane |
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29 Syntrichia |
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Plants usually smaller, to 2 cm high; leaf cells narrower; costa shortly excurrent, rarely with a hyaline awn, costa dorsal epidermis present; peristome with a low basal membrane |
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32 Tortula |
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| 22 (10) |
Leaf margins plane to only weakly recurved; peristome absent, reduced or rudimentary; perichaetia terminal or lateral |
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(23) |
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Leaf margins recurved (rarely plane); peristome teeth usually well developed, sometimes reduced; perichaetia usually terminal |
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(30) |
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| 23 (22) |
Plants densely covered with rhizoids; leaves usually linear-lanceolate; capsules lateral |
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(24) |
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Plants with rhizoids at the base; leaves lanceolate; capsules terminal |
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(25) |
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| 24 (23) |
Costa ventral epidermis absent; leaves strongly keeled, base not clearly differentiated |
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2 Anoectangium |
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Costa ventral epidermis present; leaves plane, base clearly differentiated |
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20 Molendoa |
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| 25 (23) |
Peristome reduced or rudimentary |
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(26) |
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Peristome absent |
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(28) |
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| 26 (25) |
Plants only to 4 mm tall; leaf apices blunt; costa ending below the apex, with ventral stereid band weakly developed; annuli highly vesiculous |
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13 Gyroweisia |
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Plants larger than 5 mm, to 25 mm tall; leaf apices acuminate; costa percurrent to shortly excurrent, with ventral stereid band well developed; annuli not or weakly vesiculous |
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(27) |
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| 27 (26) |
Stem central strand absent; leaf margins serrulate above the shoulder; leaves channeled |
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10 Eucladium |
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Stem central strand present; leaf margins entire; leaves not channeled |
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34 Tuerckheimia |
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| 28 (25) |
Leaves three-ranked, sheathing at the base; leaf cells smooth, basal marginal cells differentiated; costa dorsal epidermis present |
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26 Reimersia |
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Leaves multi-ranked, not sheathing at the base; leaf cells papillose, basal marginal cells not differentiated; costa dorsal epidermis absent |
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(29) |
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| 29 (28) |
Costa ending 2-5 cells below the apex, costal ventral epidermis present; stem central strand present |
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12 Gymnostomum |
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Costa usually excurrent as a mucro, costal ventral epidermis absent; stem central strand absent |
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16 Hymenostylium |
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| 30 (22) |
Stem central strand absent; leaves coarsely dentate above, high-sheathing at the base; upper leaf cells strongly thick-walled; perichaetial leaves usually strongly differentiated, convolute-sheathing |
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18 Leptodontium |
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Stem central strand present; leaf margins entire or crenulate, leaves low-sheathing or scarcely differentiated at the base; perichaetial leaves somewhat differentiated or only half-sheathing |
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(31) |
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| 31 (30) |
Leaves ligulate to spathulate; margins plane or broadly incurved; leaf cells mammillose-bulging or smooth; peristome absent |
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17 Hyophila |
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Leaves mostly lanceolate or lanceo-lingulate; margins usually recurved; leaf cells with bifid papillae, rarely simple; peristome present, rarely absent |
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(32) |
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| 32 (31) |
Perichaetial leaves with a high-sheathing base; setae 4-6 mm long; peristome absent |
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4 Bellibarbula |
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Perichaetial leaves without a high-sheathing base; setae 5-20 mm long; peristome present |
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(33) |
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| 33 (32) |
Leaves lanceo-lingulate; leaf cells pellucid, less densely papillose or nearly smooth; cells of adaxial surface of costa mostly rounded quadrate or rarely short-rectangular, papillose or smooth, thin-walled; inner perichaetial leaves small |
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15 Hydrogonium |
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Leaves narrowly ovate-lanceolate; leaf cells not pellucid, densely papillose; cells of adaxial surface of costa mostly rectangular to narrowly rectangular; inner perichaetial leaves large |
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(34) |
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| 34 (33) |
Leaf basal cells well differentiated, lax and thin-walled; margins often irregularly serrate near the apex; leaves becoming reddish when old |
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5 Bryoerythrophyllum |
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Leaf basal cells not particularly differentiated, firm- to thick-walled; margins usually entire; leaves not becoming reddish when old |
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(35) |
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| 35 (34) |
Upper leaf cells short-rectangular to rounded rectangular, usually densely papillose, cells less pellucid; costa dorsal and ventral stereid bands well developed; axillary hairs 4-10 cells long; peristome teeth 32, mostly wound together and twisted |
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3 Barbula |
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Upper leaf cells rounded quadrate or rhombic, smooth or bluntly papillose, cells pellucid; costa ventral stereid band weakly developed; axillary hairs 3-4 cells long; peristome teeth 16 or 32, erect, obliquely or weakly spiraled |
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9 Didymodon |
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List of lower taxa
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