Liverwort

Riccia violacea M. A. Howe, Ann. Mo. Bot
Gard. 2; 51. 1915.
Thalli small, 1.5-5 mm. long, simple or 1-4 times dichotomous, irregularly gregarious, rather obscurely and finely reticulate and dark-green above, dark-violet or blackish at margins and on sides, this color encroaching on upper surface here and there; main segments oblongobovate or linguiform, 0.6-1.25 mm. wide, the apices obtuse or emarginate; margins obtuse or rounded, commonly erect-connivent or inflexed on drying, bearing, especially toward the apex and often low on the sides, numerous or occasional violet or sometimes hyaline conic or subcylindric acute or obtuse papillae 20-110 m long and 25-45 ii broad at base; median sulcus shallow or obsolete except at apex; scales very short or rudimentary, dark-violet, rarely overlapping, commonly divided into a series of small irregular often tooth-like laciniae, each consisting of only a few cells; transverse sections 1.5-2 times as broad as high, planoconvex, flattened-semiorbicular, or occasionally biconvex; dorsal epidermis 2-stratose, the cells of the primary stratum thin-walled, subhemispheric or mammiform, soon collapsing and leaving inconspicuous vestiges, the cells of the secondary superficial stratum mostly 18-30 M broad. Dioicous (?); antheridial ostioles elevated 20-150 m» often violet; spores soon fuscous and very opaque, 65-105 m in maximum diameter, obscurely angled or flattenedsphaeroid, destitute of wing-margins, finely, irregularly, and almost uniformly areolate over the whole surf roe, the areolae 3-8 ju wide, soon very obscure and the spores commonly appearing minutely and densely verruculose, the verruculae obtuse or truncate, finally 2-4 /i high.
Type locauty: Mona Island, near Porto Rico.
Distribution: Sonera and Durango; Bahamas; Cuba; Porto Rico.

Riccia violacea là một loài rêu trong họ Ricciaceae. Loài này được M. Howe mô tả khoa học đầu tiên năm 1915.