3. Leucodon Schwägr.   白齿藓属   bai chi xian shu

Sp. Musc. Frond., Suppl. 1(2): 1. 1816. Neckera sect. Leucodon (Schwägr.) Müll. Hal., Syn. Musc. Frond. 2: 91. 1850.

Leucodon subgen. Leucodontella (Nog.) Nog., J. Jap. Bot. 43: 459. 1968. Leucodontella Nog., J. Hattori Bot. Lab. 2: 39. 1947.

 

Plants medium-sized to robust, pale green to green, yellowish green or dark green, or yellowish brown to brown, in loose or dense tufts or mats. Primary stems creeping, stoloniform; secondary stems ascending, irregularly or sparsely pinnately branched, sometimes with pendulous or flagelliform branches; central strand present or absent; paraphyllia absent; pseudoparaphyllia filamentous or foliose, or absent; branches mostly erect, rarely curved, often julaceous, obtuse or attenuate at the apex. Stem leaves oblong-ovate or lanceolate to linear-lanceolate, concave, plicate, shortly acute to acuminate or slenderly acuminate at the apex; margins entire or somewhat serrulate near the apex; costae absent; median leaf cells rhomboidal to linear, thick-walled or sinuous; marginal and alar cells short, irregularly quadrate or elliptic, forming a distinct alar group, extending up to 1/15–3/5 the leaf margins at the base; branch leaves similar to stem leaves; flagelliform branch leaves triangular. Dioicous. Inner perichaetial leaves large, highly sheathing at the base, shortly acuminate at the apex. Setae elongate, smooth or roughened; capsules usually symmetric, spherical, ovoid or oblong-ovoid to cylindrical, dark brown; opercula conic or shortly rostrate; annuli differentiated, often with inflated cells; stomata present or absent; peristome double; exostome teeth lanceolate, papillose and hyaline above; prostome often present; endostome segments linear or often reduced, membrane-like, sometimes absent. Calyptrae cucullate, smooth. Spores spherical, smooth or papillose.

 

1. Ascending and pendulous branches often circinate; capsules yellow, with stomata on apophyses; spores maturing in late summer or early autumn; endostome segments linear, shorter than the teeth, prostome absent......................................................... 8. L. pendulus

1. Ascending and pendulous branches not circinate (only somewhat curved in L. tibeticus); capsules brown or blackish brown, with or without stomata on apophyses; spores maturing in winter; endostome membrane-like or rudimentary, prostome often present.......................................................................................................... 2

2. Stems with a central strand.................................................................................................................................. 3

2. Stems without a central strand............................................................................................................................. 7

3. Stem leaves narrowly lanceolate, 4.0–5.2 mm long; alar cells extending up to 1/8–1/7 the leaf length...........

3. Stem leaves ovate-lanceolate, less than 4.0 mm long; alar cells extending up to ca. 1/3 the leaf length......... 4

4. Stem leaves less than 2.6 mm long; prostome one layer; brood bodies present in leaf axils................ 10. L. sciuroides

4. Stem leaves more than 2.6 mm long; prostome 2–3 layers; brood bodies absent.......................................... 5

5. Stem leaves slenderly acuminate at the apex; capsules oblong-ovoid to cylindrical, 2.2–3.7 mm × 1.0 mm...

5. Stem leaves shortly acuminate at the apex; capsules ovoid, 1.1–2.1 mm × 0.7–1.0 mm.................................. 6

6. Ascending branches straight; stem leaves 2.8–3.4 mm long; median leaf cells 28–48 µm × 3–7 µm, thin-walled to somewhat thick-walled; alar cells extending up to 1/3–2/5 the leaf length......... 9. L. sapporensis

6. Ascending branches curved; stem leaves 2–3 mm long; median leaf cells ca. 32 µm × 6 µm, thick-walled; alar cells extending up to 2/3 the leaf length.............................................................................. 16. L. tibeticus

7. Ascending branches pinnately branched.................................................................................. 6. L. jaegerinaceus

7. Ascending branches irregularly branched............................................................................................................... 8

8. Pendulous branches well developed, usually longer than the ascending branches (to ca. 15 cm long)..........

8. Pendulous branches somewhat developed, usually shorter than the ascending branches.............................. 9

9. Capsules large, spherical, with stomata on apophyses....................................................... 13. L. sphaerocarpus

9. Capsules ovoid or oblong-ovoid, without stomata.............................................................................................. 10

10. Stem leaves linear-lanceolate......................................................................................................................... 11

10. Stem leaves lanceolate, ovate or oblong-ovate, shortly acute to long-acuminate...................................... 12

11. Upper leaf cell walls porose; alar cells extending up to ca. 1/5 the leaf length; pendulous branches often present................................................................................................................................7. L. morrisonensis

11. Upper leaf cell walls not porose; alar cells extending up to (1/10–)1/7–1/4(–3/5) the leaf length; pendulous

 branches rarely developed............................................................................................................... 3. L. exaltatus

 12. Alar cells extending up to ca. 3/5 the leaf length; stem leaves 2.2–2.8 mm long................ 2. L. coreensis

 12. Alar cells extending up to ca. 1/3 the leaf length; stem leaves to 4 mm long........................................... 13

 

13. Stem leaves rounded-ovate at the base, narrowly acuminate at the apex........................................................ 14

13. Stem leaves oblong-lanceolate, narrowly acute to shortly apiculate.............................................................. 15

  14. Inner perichaetial leaves 7.0–7.5 mm long; capsules ovoid, ca. 1.5 mm × 1.0 mm; setae 4–6 mm long; spores 55–64 µm in diameter.................................................................................................... 12. L. sinensis

 14. Inner perichaetial leaves 4.0–5.0 mm long; capsules cylindrical, 2.2–2.8 mm × 0.7–1.0 mm; setae 8–15 mm long; spores 27–35 µm in diameter........................................................................ 15. L. temperatus

15. Alar cells of stem leaves extending to 1/10–1/7 the leaf length; median leaf cells 33–36 µm long, not or weakly

 porose; restricted to calcareous rocks or moist soil....................................................................... 1. L. alpinus

15. Alar cells of stem leaves extending to 1/7–1/4 the leaf length; median leaf cells 50–70 µm long, distinctly porose;

 usually on tree trunks, rarely on rocks....................................................................................... 5. L. formosanus