Ranunculus - Buttercups
Ranunculus is a large genus of around 600 species in the buttercup family, Ranunculaceae, with a global distribution. The Latin name means little frog, which is a reference to their preference to moist soil. Most flower in spring or early summer, usually yellow flowers, but a few flower white or greenish flowers. They prefer sunny positions.
Rhodiola - Stonecrops
Rhodiola is a genus in the family Crassulaceae, native to mountains and arctic regions in the northern hemisphere, the majority in China. One species is native to Iceland. (*)
Rodgersia is a small genus in the Saxifragaceae family, all native to E-Asia. They are grown in gardens for their large, bronze coloured leaves, but flower rarely in Iceland. They grow in shady places along streams in their native habitats, so they need moist soil and semi-shade.