Riella

Riella is a genus in the liverwort family Riellaceae, and includes about eighteen species. Plants in the genus are small and grow submerged in shallow temporary pools. Although the genus is widely distributed in the Northern Hemisphere, locating populations is often difficult. Its occurrence is sporadic and local, and the tiny plants are ephemeral. The ornamented spores remain viable for several years, allowing the plants to survive annual drying of their habitat. The plants are easily grown in laboratory cultures.

==Description== Riella plants are small, usually or less, and thalloid, with an appearance like an immature alga. The plant consists of an erect central axis ("stem") that is commonly forked, but only sparingly, and the plants are bright green.