Oxalis oregana – our own native shamrock

Northwest native shamrock-like Oxalis oregana; photo by nordique via Creative Commons License

With St. Patrick’s Day approaching, we thought it would be a good time to highlight a beautiful Northwest native plant that resembles a shamrock. Oxalis oregana, or redwood sorrel or Oregon oxalis, is a small herbaceous perennial that blooms from early spring through summer. They’re native to the U.S. West Coast, from British Columbia south to California. In Washington state, you may encounter them as thick, lush carpets of green in coastal forests, such as those in the Olympic National Park.

Oxalis oregana has three shamrock-like heart-shaped leaflets, with a deep green color. The plants, however, most commonly portrayed as shamrocks are: Oxalis acetosella (wood sorrel), Trifolium repens (white clover), or Medicago lupulina (black medic), or Trifolium minus (hop clover).

Our native redwood sorrel spreads by creeping rhizomes (through horizontal rootstalks), and can spread quickly once established. It’s well-suited for partial shade or deep shade areas;   blooms in spring bearing white or pink flowers about an inch wide; and dies back in the winter in cold areas.