Mystery Plant: Oxalis articulata

Oxalis articulata, pictured, is known more commonly as Windowbox wood-sorrel or Red wood-sorrel.
Oxalis articulata, pictured, is known more commonly as Windowbox wood-sorrel or Red wood-sorrel. Special to The Herald-Sun

Remember Saint Patrick's Day? Here is a plant, now in full bloom, which might stir your memory.

Its leaves are compound, each one bearing three deep-green, valentine-shaped leaflets, and thus it appears to be a sort of shamrock. The problem is that the little green plant we celebrate as Saint Patrick's shamrock may in fact be a species of clover, in the bean family…which also has a similar leaf, and which also grows in Ireland. It may be impossible to determine, absolutely, which plant represents the traditional shamrock of Irish legend. Once again, the problem stems from the use of common names, rather than scientific names. ("Clovers" all belong to the genus Trifolium.)

Anyway, our mystery plant is certainly not a clover species of any sort, nor is it a member of the bean family at all. As similar as its leaves are to those of clover, its flowers are much different. Borne in clusters atop softly downy stalks, these flamboyant, star-like blossoms bear five bright pink (sometimes white) petals, often finely striped. Ten stamens will be present inside a flower, forming two whorls, with five short and five long. After the flowers fade, greenish capsules will develop, containing a number of tiny, reddish seeds. Eventually these angled little pods will burst, scattering the seeds everywhere.

Some of its common relatives have yellow flowers. Another closely related species has speckled leaflets, and grows in rich woods here in the Southeast. All totaled, there about 800 species of its genus around the world.

You can see our Mystery Plant growing nearly throughout the southern states. It is a native of South America, but has escaped its garden confines, frequently showing up in lawns and along sidewalks, forming patches or clumps. Just the other day, while mowing my lawn, I purposefully spared a patch of it from the whirling blades: it’s awfully pretty, I think. However, its weedy tendencies make it a nuisance to some, and if you want to get rid of it, start digging its scaly, bulbous roots — now. (Actually, these things are technically what we call “corms,” a lot like what a gladiolus will make below ground.) Once it really gets warm, the top parts of the plant will disappear, and then of course, you can’t spot it above the ground.

Now many people know this plant by its taste: it is sour. In fact, an old name for this plant, and its relatives, is "sorrel", which comes from an archaic word meaning sour. This taste is derived from a fairly high concentration of oxalic acid, which can be somewhat poisonous in large amounts. Some species are eaten as a salad green…and I've heard locally that it makes a fine sandwich, slathered with mayo and between two pieces of white bread. (Dee-lish!)

EDITOR’S NOTE — John Nelson is the curator of the A. C. Moore Herbarium at the University of South Carolina, in the Department of Biological Sciences, Columbia, S.C. 29208. The Herbarium offers free plant identifications. For more information, visit, call 803-777-8196, or email