Oxalis corniculata

Oxalis corniculata
afternoon -- flowers open, leaves closed

morning -- flowers closed, leaves open

Oxalis corniculata is commonly known as Yellow Woodsorrel, or Creeping Woodsorrel. It grows as a weed in my lawn, and the "creeping" aspect keeps it below the level of the lawnmower. Like other sorrels or docks, it is known for its lemony flavor, which comes from the oxalic acid content. This plant's flavor is better than most. It is lemony and juicy, without any of the bitterness which is common in other sorrels and docks.

The oxalic acid has some downsides. The main caution is that is can contribute to causing kidney stones, so your should avoid it if you have problems with those. It can bind to minerals and prevent their intake by the body. Thus it can prevent calcium and iron absorption, but on the other hand it could be helpful if you want to eliminate minerals from your body. It is a common compound in leafy greens. Rhubarb and spinach are often cited as being high in oxalates. The plants with enough that you can taste the lemony flavor of it are especially high in oxalic acid, and it takes its name from this Oxalis genus of plants.

I enjoy the taste of Oxalis corniculata as an occasional treat, because the flavor is very good. The leaves, flowers, and fruit (all the above-ground parts) are all edible and taste about the same. It makes a nice addition to salads, where a bit of lemon flavor is often a welcome addition. Instead of adding lemon juice to your salad dressing, just add some Oxalis instead.

There are many other species of Oxalis, which have similar flavors. I have eaten Oxalis oregana (Redwood sorrel), for example, while visiting the redwood forests in California.

The main identifying feature of the Oxalis genus is the leaves. They are heart-shaped and come in threes, so they look a lot like clover leaves. They often have different shades on the top and bottom. Oxalis corniculata is green on both sides, but Oxalis oregana is green on the top and often purple on the bottom. There is an ornamental variety of Oxalis which is dark purple on both sides. The leaves are light-sensitive, usually closing at night and opening during the day. But I suspect they don't want too much light, because the ones in my yard tend to open in the morning and close by afternoon. The ones growing in the shady redwood forests stay open all day. The Oxalis corniculata species is distinguished by its yellow flowers, and by the fruit, which are smooth, narrow and about 1/2 to 1 cm long, and stand upright on deflexed (sideways or downward growing) stems.