Riccia albida Sull. ex Austin

Riccia albida SulL; Aust. Proc. Acad
Phila. 1869:231. 1870.
Thalli small, mostly 2-4 mm. long, 1-3 times dichotomous, irregularly gregarious, chalkwhite and more or less calcified, alveolate-reticulate or spongiose above, both when living and when dried, the margins and sides white or albescent; main segments oblong, cuneateoblong, or subquadrate, 0.7-1.1 mm. wide; terminal segments quadrate or sub quadrate-ovate, obtuse; margins obtuse and rounded, naked or minutely papillate; median sulcus narrow and rather acute, occupying one-sixth to onetenth the width of the thallus, persistent; scales minute (invisible in ordinary examination) ; transverse sections subelliptic or semiorbicular, mostly 1.5-2 times as broad as high, 18-24 cells thick in median parts, the cells of 1-6 dorsal layers decolorate with more or less calcified walls, the air-canals of the decolorate stratum often enlarged; cells of the primary stratum of the dorsal epidermis persistent, rounded-obtuse, truncate, or often mammillate or apiculate, 26-40 ii broad, extremely variable in form. Dioicous(?) ; antheridial ostioles scarcely elevated ; spores (mature?) yellowish-brown, 65-85 /x in maximum diameter, obscurely angular, wing-margins wanting, imperfectly developed, or appearing only as bosses at the four main angles, all faces nearly smooth or showing occasionally low irregular wrinkles or warts, the extine readily delaminating.
Type w>cai,ity: "Texas.*'
Distribution: Texas (Uvalde, McAllister).

Riccia albida là một loài rêu trong họ Ricciaceae. Loài này được Sull. mô tả khoa học đầu tiên năm 1869.