Riccia austini

Riccia austini Stephani, Bull. Herb. Boiss. 6: 336. 1898
Riccia lamellosa Underw. Bull. III. I^ab.Nat. Hist: 2: 24. 1884. Not R. lamellosa Raddi, 1818. Riccia lamellosa americana M, A. Howe, Bull. Torrey Club 25: 189. 1898. Riccia americana M. A. Howe, Mem. Torrey Club 7; 24. 1899.
Thalli medium-sized, mostly 6-15 mm. long, 1-4 times dichotomous, subradiate, often forming compact, more or less imbricate masses, pale-green and regularly reticulate above, concolorous below; main segments oblong, 2.5-4 mm. in greatest width; terminal segments oblong to obcordate, mostly obovate, obtuse or emarginate; margins acute, thin-membranous, or subalate, ascending, or, when dry, often erect-connivent ; median sulcus acute, narrow, and deep toward apex ; scales large, colorless, obtuse, subunduiate,. patent or somewhat imbricate, extending considerably beyond the margins; transverse sections subquadrate, oblong, or somewhat parabolic, 1.5-3 (-4) times as broad as high, 14-30 cells thick in median parts, the ventral outline rounded or subrectilinear ; dorsal epidermis 2-stratose, the cells of the primary stratum subglobose or ovoid-pap illiform, soon collapsing and leaving irregular or cuplike vestiges, the cells of the succeeding stratum 30-75 m broad, the cells of two or three subjacent strata sometimes decolorate. Monoicous; antheridial ostioles scarcely elevated or occasionally up to 150 m high; capsules with spongiose covering protuberant, finally erumpent; spores brown, 75-126 m in maximum diameter, obscurely angular, a wmg margin wholly wanting or rudimentary, the outer face with clearly defined areolae mostly 12-16 m wide, commonly showing in profile low, often obscure papillae 1-4 /x high, the inner faces with smaller much lesg distinct areolae or simply marked with low irregular vermicular ridges.
Type locality: Near Closter, New Jersey.
Distribution: Connecticut to Texas and California.