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Plagiothecium Schimp.

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Project Name Data (Last Modified On 4/1/2009)

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Project Data (Last Modified On 4/1/2009)

General Reference:

Hu, R.-L., Y.-F. Wang, M. R. Crosby & S. He. 2008. Amblystegiaceae—Plagiotheciaceae. 7: viii + 258 pp. In Moss Fl. China. Science Press & Missouri Botanical Garden, Beijing, New York & St. Louis.

Notes (Last Modified On 4/1/2009)

general taxon notes:

Plagiothecium consists of some 50 species in the world. Half of them are better understood (Crosby et al. 2000). Most species occur on rocks, rotten wood, and tree bases in the temperate regions. The historic studies of Chinese Plagiothecium include those of Müller (1896, 1898), Thériot (1925), Brotherus (1929), C. Gao et al. (1977), P. C. Chen et al. (1978), and M.-X. Zhang (1978). Twelve taxa of Plagiothecium were reported from Xizang by X.-J. Li (1985). Redfearn et al. (1996) listed 19 species and seven varieties from China. Sakurai (1941) described P. shinii Sakurai from Taiwan, but its type was not available for study. Based on its description with pseudoparaphyllia, serrate leaf apices, and non-decurrent leaf bases, it is likely a species of Taxiphyllum. A new combination is made here, Ectropothecium glossophylloides (Broth.) D.-K. Li, comb. nov. (basionym, Plagiothecium glossophylloides Broth., Symb. Sin. 4: 116. pl. 4, f. 7. 1929). It was based on the presence of filimentous pseudoparaphyllia, the absence of leaf costae, and the absence of a clear decurrency at leaf bases. Plagiothecium shevockii S. He was recently described from Taiwan by S. He (2008). Seventeen species and six varieties are treated here.

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1. Plagiothecium Bruch & Schimp. in B.S.G. 棉藓属 mian xian shu

Bryol. Eur. 5: 179. 1852. Hypnum sect. Plagiothecium (Bruch & Schimp.) Sull. in Gray, Manual (ed. 2) 679. 1856.

Plants slender to medium-sized, often complanate, green or yellowish green, usually glossy, in loose or dense mats. Stems prostrate or somewhat ascending, irregularly branched; in cross section a row of outer cortical cells enlarged, thin-walled; central strand absent or weakly to well differentiated; paraphyllia and pseudoparaphyllia absent. Stem and branch leaves similar, erect-spreading, plane, or sometimes undulate, often asymmetric, ovate to elliptical, or ovate-lanceolate, gradually or abruptly acute to acuminate, strongly decurrent at base; margins often recurved near base, sometimes throughout, entire or somewhat dentate at apex; costae double, or forked, unequal, appearing to be single, reaching 1/3–1/2 the leaf length, sometimes very short or absent; median leaf cells smooth, narrowly or elongate-rhomboidal, thin-walled; basal cells shorter, broader; alar regions often differentiated with loose, elongate-rectangular cells, thin-walled, hyaline, often strongly decurrent with long, narrow stripes in 2–3 rows. Brood bodies often present; gemmae single-celled, club-shaped, cylindrical, or fusiform, 2–7 celled, uniseriate, often clustered in leaf axils on stems and branches, sometimes borne on dorsal leaf surfaces, hyaline or light green. Autoicous or dioicous. Perichaetial leaves often sheathing at base, reflexed at apex. Setae slender, smooth, somewhat reddish when mature; capsules suberect, inclined or horizontal, symmetric or asymmetric, ellipsoidal or cylindrical, with a short neck; stomata present; opercula conic-rostrate with long, oblique beaks; annuli differentiated; peristome double; exostome teeth narrowly lanceolate, yellowish, cross-striolate below, hyaline, papillose above; endostome segments keeled, hyaline, papillose; basal membrane high; cilia 2–3, nodulose. Calyptrae cucullate, smooth. Spores spherical, nearly smooth or papillose.

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1. Leaf apex abruptly contracted to a rather long piliform, flexuose acumen............................... 12. P. piliferum

1. Leaf apex acute, acuminate or gradually and slenderly long acuminate to filiform........................................... 2

2. Plants large, whitish green; leaves strongly undulate............................................................ 17. P. undulatum

2. Plants small to medium-sized, pale to dark green or yellowish green; leaves not or only weakly undulate 3

3. Leaf bases broadly decurrent, consisting of rounded-rectangular or oval cells, not ending in a triangular shape.............................................................................................................................................3. P. denticulatum

3. Leaf bases narrowly or slenderly decurrent, consisting of rectangular or elongate cells, usually ending in a slenderly triangular shape........................................................................................................................................ 4

4. Leaves distinctly complanate-spreading, strongly asymmetrical, weakly undulate........ 9. P. neckeroideum

4. Leaves not or weakly complanate-spreading, symmetrical to somewhat asymmetrical, rarely undulate..... 5

5. Leaves moderately asymmetrical, clearly secund................................................................................................. 6

5. Leaves symmetrical, not or indistinctly secund.................................................................................................... 7

6. Dioicous; leaves ovate, usually rugose or plicate................................................................... 5. P. formosicum

6. Autoicous; leaves ovate-lanceolate, not rugose or plicate............................................................. 7. P. laetum

7. Stems without a central strand...................................................................................................... 8. P. latebricola

7. Stems with a central strand either well developed or weakly differentiated....................................................... 8

8. Cells of leaf decurrency shortly broad-rectangular, sharply different from other basal cells................ 4. P. euryphyllum

8. Cells of leaf decurrency long rectangular, not sharply different from other basal cells............................... 9

9. Branches usually not julaceous, more or less complanate; plants usually prostrate............... 2. P. curvifolium

9. Branches usually subjulaceous or julaceous, not complanate; plants often ascending.................................... 10

10. Leaves not contorted when dry; leaf cells usually linear to narrowly rectangular..................................... 11

10. Leaves distinctly contorted when dry; leaf cells hexagonal to narrowly rhomboidal................................ 12

11. Leaves broadly ovate, not ending in a filiform acumen; median leaf cells 75–96 µm × 9–12 µm........... 6. P. handelii

11. Leaves ovate-lanceolate, ending in a filiform acumen; median leaf cells 84–120 µm × 9–14 µm........ 15. P. subulatum

12. Plants not clearly glossy, somewhat dull................................................................................ 10. P. nemorale

12. Plants strongly glossy...................................................................................................................................... 13

13. Leaf apices with a group of hyaline, thin-walled, short cells........................................................................... 14

13. Leaf apices without a group of hyaline, thin-walled, short cells..................................................................... 15

14. Leaves ovate-lanceolate, asymmetric; central strand well differentiated..................... 13. P. platyphyllum

14. Leaves orbicular at base, symmetric; central strand weakly differentiated............. 14. P. shevockii

15. Leaves broadly ovate-lanceolate to oblong-lanceolate........................................................ 16. P. succulentum

15. Leaves broadly elliptical to oblong-ovate......................................................................................................... 16

16. Branches somewhat julaceous; leaf apices often secund; leaves significantly longer than wide (1.3–2.0 mm × 0.6–1.0 mm)...................................................................................................................... 1. P. cavifolium

16. Branches not at all julaceous; leaf apices not secund; leaves nearly as long as wide (1.40–1.50 mm × 1.2–1.29 mm)............................................................................................................................ 11.P. paleaceum