Monographs Details: Reboulia
Authority: Bischler, Hélène, et al. 2005. Marchantiidae. Fl. Neotrop. Monogr. 97: 1--262. (Published by NYBG Press)
Family:Aytoniaceae
Scientific Name:Reboulia
Synonyms:Reboulia hemisphaerica (L.) Raddi, Marchantia hemisphaerica L.
Description:Genus Description - Thallus 3-9 mm wide, dull green, often ringed with purple. Epidermal cells with conspicuous trigones. Epidermal pores with 3-6 rings of 6-9 cells, radial walls thickened. Air chambers in several layers. Basal tissue without mucilage cavities. Ventral scales with oil cells and marginal papillae, and 2-4 filiform appendages, not constricted basally. Monoecious. Antheridia and archegonia as in the family, archegonia 1-2 per archegonial cavity. Archegoniophore stalk without assimilatory strip, with 1 rhizoid furrow, with scales at top and bottom; receptacle 4- to 6-lobed. Calyptrae 3- to 4-layered after fertilization. Involucres bilabiate, opening obliquely downwards. Sporophyte 1 per involucre. Capsules opening to 1/3 of capsule length by a fragmenting lid. Spores 2500-3000 per capsule, 60-90 µm diam., proximal and distal faces with tuberculate areoles and tuberculate ridges, trilete scar distinct. Elaters with 2-3 helical bands. Gametophytic chromosome number n = 9 or 18.

Discussion:A genus comprising 1-3 drought-tolerant species inhabiting rock crevices and rock outcrops, recorded from relatively warm areas in both hemispheres, 62°N to 50°S. It is frequent in the Mediterranean area but is absent from areas with long, cold winters and from tropical, humid zones.