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Moss China | Family List | Moss China V. 2 | Pottiaceae

15. Hydrogonium (C. Müll.) Jaeg., Ber. Thätigk. St. Gallischen Naturwiss. Ges. 1877–78:405. 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.

Most species of Hydrogonium occur in tropical and subtropical regions of the world, most commonly on calcareous rocks in moist habitats. Twelve species are found in China.

1 Plants stiff; leaves triangular-lanceolate   (2)
+ Plants rather soft; leaves mostly ligulate   (7)
2 (1) Leaf apices acuminate   (3)
+ Leaf apices more or less blunt   (4)
3 (2) Leaf cells smooth   2 Hydrogonium arcuatum
+ Leaf cells mammillose or minutely papillose   1 Hydrogonium anceps
4 (2) Costa excurrent   10 Hydrogonium sordidum
+ Costa percurrent   (5)
5 (4) Leaf cells smooth   12 Hydrogonium williamsii
+ Leaf cells mammillose   (6)
6 (5) Costa stout; leaf cells rather thick-walled; leaf apices entire; gemmae present   4 Hydrogonium gangeticum
+ Costa slender; leaf cells thin-walled; leaf apices serrulate; gemmae absent   5 Hydrogonium gracilentum
7 (1) Costa shortly excurrent   (8)
+ Costa percurrent or ending a few cells below the apex   (9)
8 (7) Lower leaf margins revolute; gemmae present, filiform or spindle-shaped   8 Hydrogonium majusculum
+ Lower leaf margins plane, not revolute; gemmae absent   9 Hydrogonium pseudo-ehrenbergii
9 (7) Leaves broader, ovate-ligulate   7 Hydrogonium javanicum
+ Leaves narrower, lanceo-ligulate   (10)
10 (9) Leaf cells distinctly papillose; upper leaf margins serrulate   11 Hydrogonium subpellucidum
+ Leaf cells smooth or rarely mammillose; upper leaf margins entire   (11)
11 (10) Leaves plane; leaf apices rounded; costa ending below the apex   3 Hydrogonium ehrenbergii
+ Leaves plicate; leaf apices somewhat apiculate; costa percurrent   6 Hydrogonium inflexum

  • List of lower taxa


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