Monographs Details: Riccia grandis Nees
Authority: Bischler, Hélène, et al. 2005. Marchantiidae. Fl. Neotrop. Monogr. 97: 1--262. (Published by NYBG Press)
Scientific Name:Riccia grandis Nees
Synonyms:Riccia flavispora Steph.
Description:Species Description - Thalli in rosettes of 10-15 mm diam.; lobes thin, flat, 2-3 times forked, with deep dichotomies, 6 mm long, 2-4 mm wide, obtuse and shortly bilobed apically; dorsal side greenish; ventral side pale green. Median groove shallow, only apically distinct. Epidermal cells disintegrating. Ventral scales hyaline or violet, extending beyond lobe margins. Cross section of lobes 3-6 times as wide as high, with 12 thin-walled cell layers of which 4 are dorsal tissue; dorsal edge acute or obtuse laterally; flanks indistinct, the hardly convex ventral edge extending progressively into the flanks. Monoecious. Antheridial necks protruding, white. Sporangia hardly bulging, light yellow. Spores tetrahedral, 80-95 µm diam., reddish brown; wing light brown, irregular, 5 µm wide, granulose; distal face with 8-10 areoles across diam., with narrow ridges and thin, high tubercles; proximal face with numerous complete areoles with low, wide ridges and tubercles, triradiate scar with wide ridges not reaching the equator.

Discussion:Riccia grandis is somewhat related to R. sorocarpa, but the spores in R. grandis have complete areoles on the proximal face, whereas in R. sorocarpa the proximal face is granulose-tuberculate, not areolate.
Distribution:São Paulo Brazil South America| Rio de Janeiro Brazil South America|