Riccia campbelliana M. Howe

Riccia campbelliana M. A. Howe, Mem. Torrey Club 7:
26. 1899.
Thalli medium-sized or rather large, 4-18 mm. long, once or twice or occasionally three times dichotomous, rarely subradiate, loosely gregarious, lightor brownish-green and reticulate above, brown or nearly concolorous below or very rarely blackening, often subcarinate; main segments oblong or linear-oblong, 1-3 mm. (mostly 1.5-2 mm.) wide; terminal segments oblong or obovate, obtuse, less commonly subacute; margins thin, naked, membranous, commonly yellowish -brown, now and then abruptly winged, on drying usually ascending, erect, or inflexed-connivent; rdedian sulcus acute, often obscure toward base; scales brown or nearly colorless, usually inconspicuous, but sometimes slightly exceeding the margin at apex ; .transverse sections (without margins) subquadrate or oblong, and including margins, 2-5 (mostly 2.5) times as broad as high, 25-35 cells thick m median parts, the ventral outline rounded; dorsal epidermis unistratose, the cells of the primary stratum large, 25-80 fx broad, elliptic-oblong, mostly higher than broad, long-persistent; oil-body cells usually numerous. Monoicous; antheridial ostioles prominent, conic-cylindric, 100-170 m high; capsules commonly
numerous, finally erumpent and exposing the spores; spores finally yellowish-brown, 75-108
M (mostly 90-100 fx) it maximum diameter, distinctly angular, with a minutely granulate or
nearly smooth margin 3-6 m in width, the outer face lightly papillate or nearly smooth in
profile, marked with close sinuous ridges which rarely form complete meshes, the imperfect
areolae mostly 4-7 ju wide, the inner faces similarly but less strongly marked.
Type locality: Near Stanford University, California. Distribution: Texas and California.

Riccia campbelliana là một loài rêu trong họ Ricciaceae. Loài này được M. Howe mô tả khoa học đầu tiên năm 1899.