Oxalis oregana (redwood sorrel, Oregon oxalis) is a species of the wood sorrel family, Oxalidaceae, native to moist Douglas-fir and coast redwood forests of western North America from southwestern British Columbia, Washington, Oregon, and California.
Oxalis oregana is a short, herbaceous perennial plant with erect flowering stems 5–15 cm tall. The three leaflets are heart-shaped, 1–4.5 cm long with purplish undersides, on 5–20 cm stalks. The inflorescence is 2.4–4 cm in diameter, white to pink with five petals and sepals. The hairy five-chambered seed capsules are egg-shaped, 7–9 mm long; seeds are almond shaped.
Redwood sorrel, Oxalis oregana, photosynthesises at relatively low levels of ambient light (1/200th of full sunlight). When direct sunlight strikes the leaves they fold downwards; when shade returns, the leaves reopen. Taking only a few minutes, this movement is observable to the eye.
- Burke Museum — WTU Herbarium Image Collection
- Plant Profile for Oxalis oregana — USDA Plant Database
- SAPS — Science And Plants for Schools
- E-Flora BC — Electronic Atlas of the Plants of British Columbia
- Light interception and utilisation — Plants in Action: Adaptation in Nature, Performance in Cultivation
- Pojar, Jim; Andy MacKinnon (2004). Plants Of The Pacific Northwest Coast: Washington, Oregon, British Columbia & Alaska. Lone Pine Publishing. ISBN 978-1-55105-530-5.
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