Riccia donnellii

Riccia donnellii Aust. Bull. Torrey Club "6: 157. 1877
Thalli large, commonly 10-12 mm. long, subsimple or 1-5 times dichotomous, at first subradiate, becoming irregularly gregarious, of a bright clear light-green and with a crystalline lustre when living, lighter-green and reticulate when dry, concolorous or occasionally brownish below, alate-carinate, the carina at times incrassate anteriorly and developing a descending pedunculate tuber; main segments linear to short-oblong, and obcordate, 2-7 mm. wide; terminal segments obovate, obcordate, or oblong, obtuse or emarginate; margins thin and alate, ascending in younger parts, elsewhere nearly plane, bearing a few or rather numerous short, stout, obtuse, sometimes geminate cilia 100-325 /* long and 75-150 /* in greatest width; median sulcus narrow, deep, and often abruptly closed in front, soon broadening and commonly disappearing in older parts; scales rudimentary or inconspicuous; transverse sections (without wing) semiorbicular or parabolic and (including wing) 1-4 times as broad as high; dorsal epidermis 2-stratose, the cells of the primary stratum subhemispheric or ovoid-ellipsoid, mostly 45-85 )u broad, obtuse or occasionally mammillate, soon collapsing and leaving irregular vestiges, the cells of the succeeding stratum mostly 75-150 m broad, commonly broader than high. Dioicous, antheridial thallus often narrower; antheridial ostioles numerous, much elevated, 200-800 M high; capsules usually numerous, 0.75-1 mm. in diameter, often crowded in a single or somewhat double row; spores soon black and very opaque, 130-190 m in maximum diameter, angular, with a nearly smooth or lightly granulate margin 2-6 m wide, the outer face areolate, in profile smooth or showing obscure truncate verrucae 2-4 ju high, the areolae (visible only in young stages) mostly 10-14 ju wide, the inner faces similarly but a little less strongly marked.
Type locality; Jacksonville, Florida. Distribution: Florida and Texas.