Dryas (plant)
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 Dryas × suendermannii | ||||||||||||
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Dryas is a genus of dwarf perennial herbaceous plants in the rose family Rosaceae, native to the arctic and alpine regions of Europe, Asia and North America. The genus is named after the Greek nymph Dryas.
There are three species and one hybrid:
- Dryas drummondii – Drummond's Avens
- Dryas integrifolia – Entire-leaved Avens
- Dryas octopetala – Mountain Avens
- Dryas × suendermannii – D. drummondii × D. octopetala
The species are superficially similar to Geum, Potentilla and Fragaria, but are distinct in having flowers with eight petals (rarely seven or up to ten), instead of the five petals found in most other genera in the Rosaceae. The flowers are erect and white with a yellow centre (Dryas integrifolia, Dryas octopetala) or pendulous and all-yellow (Dryas drummondii), and held conspicuously above the small plants. The hybrid has pale yellow flowers. This makes them very popular in rockeries and alpine gardens.
The classification of Dryas within the Rosaceae is presently unclear. The genus was originally placed in the subfamily Rosoideae, and later in subfamily Dryadeae along with the genera Chamaebatia, Purshia and Cercocarpus, all four genera sharing root nodules that host the nitrogen-fixing bacterium Frankia. However, recent genetic research indicates that Dryadeae may be paraphyletic, with Dryas not closely related to the other three genera.
References
- Germplasm Resources Information Network: Dryas
- Huxley, A. (1992). New RHS Dictionary of Gardening. Macmillan [D. × suendermannii].