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Oxalis oregana


"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.[3]" 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.[4][5]


I found this beautiful patch of Oxalis on Pete's Trial at Col Bob, Washington. Oxalis oregana grows in dense forests, where there is plenty of water, nearby creeks, or in areas where there's been a lot of rainfall.


The leaves of Oxalis oregana were eaten by Native Americans, probably in small quantities, since they contain mildly toxic oxalic acid, whence the genus name. I personally have snacked on Oxalis all my life and have never gotten sick; the taste is very sour and I love it! We've always called it sour grass, but another common name is Redwood Sorrel. I suppose I won't ever eat large quantities of sour grass, because it is mildly toxic.

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Washington, USA

Spotted on Jul 3, 2011
Submitted on Dec 24, 2012


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