The Urban Pantheist

Urban species # 072: Wood sorrel Oxalis stricta

Just in time for Saint Patrick's day we have our first wood sorrel sprouts in Boston. Also called shamrock, and a whole host of other common names, this widespread weed is a familiar fixture in urban and suburban spaces. Sometimes its confused with clover, because it has three leaflets, but wood sorrel's leaflets are heart shaped. Its flowers are yellow and five-petaled, while clover flowers are compound clusters of white or pinkish flowers arranged in a puff.

Wood sorrel belongs to the large genus Oxalis, and gardeners will usually refer to it, disparagingly, by this name. The plant has pleasantly sour taste. I remember my mother plucking its leaves and nibbling them; it was my first realization that wild plants can be edible. It is sour because it's one of many plants rich in oxalic acid, including rhubarb and spinach. Too much oxalic acid has negative nutritional effects, and eating many handfuls of wood sorrel may earn you a stomach ache. Oxalic acid in its pure state can be used to bleach wood and remove rust.

Wood sorrel thrives in a wide variety of habitats. It does well in disturbed soil, which makes it a prime candidate for urban environments. It doesn't compete well with taller plants, making it a common plant at the edges of lawns and paths.

( One more sad little early spring wood sorrel )