15. Hydrogonium (C. Müll.) Jaeg.    石灰藓属   shi-hui xian shu

Ber. Thätigk. St. Gallischen Naturwiss. Ges. 1877–1878: 405. (Ad. 2: 669). 1880.

 

Plants mostly medium-sized to large, sometimes small, usually grayish green, in dense tufts. Stems erect or inclined, simple or branched; central strand present. Leaves appressed, rarely contorted when dry, erect-spreading when moist, triangular- to ovate-lanceolate or ligulate, acute or blunt at the apex, plane or weakly keeled in the upper ¹¤₃ leaf length; margins mostly plane, occasionally revolute, entire, rarely serrulate near the apex; costa stout, percurrent to shortly excurrent, with 2 stereid bands in cross section, cells of adaxial surface of costa quadrate to short-rectangular, papillose or smooth, thin-walled; upper leaf cells loose, usually quadrate to hexagonal, thin-walled, mostly smooth, rarely mammillose or papillose, well defined in surface view; basal cells rectangular, smooth, hyaline. Gemmae usually present, in various shapes. Dioicous. Perichaetial leaves smaller than stem leaves, not sheathing at the base. Setae slender, straight, yellowish; capsules erect, cylindrical; annuli differentiated; peristome teeth linear, usually erect, rarely twisted counterclockwise; opercula long conic-rostrate. Calyptrae cucullate, smooth. Spores spherical, brownish, finely papillose.

1. Plants stiff; leaves triangular-lanceolate............................................................................................................... 2

1. Plants rather soft; leaves mostly ligulate.............................................................................................................. 7

2. Leaf apices acuminate..................................................................................................................................... 3

2. Leaf apices more or less blunt....................................................................................................................... 4

3. Leaf cells smooth............................................................................................................................ 2. H. arcuatum

3. Leaf cells mammillose or minutely papillose................................................................................... 1. H. anceps

4. Costa percurrent.............................................................................................................................................. 5

4. Costa excurrent...................................................................................................................... 10. H. sordidum

5. Leaf cells smooth......................................................................................................................... 12. H. williamsii

5. Leaf cells mammillose........................................................................................................................................... 6

6. Costa stout; leaf cells rather thick-walled; leaf apices entire; gemmae present............ 4. H. gangeticum

6. Costa slender; leaf cells thin-walled; leaf apices serrulate; gemmae absent................. 5. H. gracilentum

7. Costa shortly excurrent.......................................................................................................................................... 8

7. Costa percurrent or ending a few cells below the apex....................................................................................... 9

8. Lower leaf margins revolute; gemmae present, filiform or spindle-shaped.................. 8. H. majusculum

8. Lower leaf margins plane, not revolute; gemmae absent................................... 9. H. pseudoehrenbergii

9. Leaves broader, ovate-ligulate...................................................................................................... 7. H. javanicum

9. Leaves narrower, lanceo-ligulate......................................................................................................................... 10

10. Leaf cells distinctly papillose; upper leaf margins serrulate.................................. 11. H. subpellucidum

10. Leaf cells smooth or rarely mammillose; upper leaf margins entire..................................................... 11

11. Leaves plane; leaf apices rounded; costa ending below the apex.......................................... 3. H. ehrenbergii

11. Leaves plicate; leaf apices somewhat apiculate; costa percurrent............................................. 6. H. inflexum