Riccardia palmata
Marchantiophyta
Riccardia palmata (Aneuraceae)
Palmate Germanderwort
Infrequent
Distinguishing Features
Riccardia palmata is the smallest regional species in the genus, presenting on decaying wood and organic matter in wet coastal regions as once-branched, elongate and deep green thallus segments typically less than 5 mm long and .5 mm wide. The thallus round in profile and barely clears its substrate. Aside from its small size, the plant is distinguished by its sexual condition, whereby archegonia and antheridia are produced on seperate plants ("dioicous").
Similar species
On account of its small size, rounded, undifferentiated thallus and linear growth, R. palmata unlikely to be mistaken for any other genus of liverwort in the region. Riccardia chamedryfolia is a much larger plant that exhibits many branches along a jagged main thallus, while in R. palmata, the plant is little branched (once to twice at most). R. multifida, in addition to being larger, has a characteristic wing of thin tissue along the edge of the thallus, while in R. palmata, there is no wing. R. latifrons, while also larger, is most similar and tends to grow on the same decaying wood and organic matter. When sterile, it is hard to tell apart from R. palmata, except on the basis on size. Close examination of either fresh or fertile material can distinguish the two: R. latifrons lacks oil bodies under the microscope and has archegonia and antheridia on the same plant ("Monoicous"). Oil bodies are present in R. palmata and the archegonia and antheridia occur on seperate plants ("dioicous").
Habitat
Moist to wet, shady decayed wood along streambanks, or occasionally peatlands, rarely on rock outcrops or cliffs, in the lowland and montane (rare) zones
Associated species