[The Oxalis Family in the Cascade Mountains of Oregon and Washington]
Western Wood Sorrel,
Oregon Wood Sorrel, Redwood Sorrel, Redwood-sorrel, Sour Grass
Oxalis oregana
Synonyms: Oxalis oregana var. oregana, Oxalis oregana var. smallii
Oregon wood sorrel as seen at the author's garden in Gresham, OR..............May 11, 2009. This variety of wood sorrel makes an attractive ground cover for the woodland garden to the west of the Cascade Mts.
-- 
Close-ups of the flower and "shamrock" leaf and flower of western wood sorrel as seen in the author's garden in Gresham, OR..............May 5, 2009.
Paul Slichter