Scientific name: Oxalis violacea
Common name: Violet wood sorrel
(Information for this species page was compiled in part by
Nicole Leninger for Biology 220M at Penn State New Kensington in Spring 2002)
wood sorrel is a small, perennial wildflower found in open woodlands, moist
prairies, thickets and waste areas from New England west to South Dakota, and
south to Florida, Georgia, Louisiana, and Texas. Other names for this plant
include “sheep sorrel,” “sour clover,” “trinity grass,” and “Indian lemonade.”
These common names reflect a number of important morphological, physiological
and ecological aspects of the plant: it can come to be quite abundant in sheep
pastures (because sheep, like most herbivores, avoid eating it), it has a
tri-parted leaflet (hence the “trinity”) that resembles the leaflets of clover,
and it has sour tasting, acidic leaves (that can be used to brew a lemonade-like
beverage). The scientific name of the genus (Oxalis) reflects the
abundance of oxalic acid in the plant’s leaflets and stalks. Crystalline
deposits of oxalic acid can even be found in the plant’s apical notch. The high
concentrations of this sour tasting and mucous membrane irritating chemical
explains the reluctance of most herbivores to consume this plant.
Habitat and Range
Violet wood sorrel grows best in sites with moderate to
high levels of sunlight. Deeply shaded woods, then, are not ideal habitats for
this species. The presence of violet wood sorrel is, in fact, a good indication
that somewhere in a site’s history an open woodland or savanna-like habitat was
In Massachusetts, violet wood sorrel is a “threatened”
species and is found only in very limited sites and areas of the state. Its
occurrence, though, in forty of the forty-eight contiguous states reflects its
generally widespread distribution and robustness. Fire encourages flowering in
colonies of violet wood sorrel. This positive response to fire probably is
reflective of the species’ evolutionary history and association with prairie
Violet wood sorrel grows from rose-colored, subterranean
bulbs. Its three-lobed, heart-shaped (“clover-like”) leaflets rise on short
stalks to just above the soil surface. Taller (four to eight inches) flower
stalks rise up over the leaflets. The flowers are small (half an inch or less
wide), three petaled, and colored dark pink to purple.
Violet wood sorrel flowers in the spring and early summer.
The petals open in the morning (between 8:00 and 9:30 am) but will remain
tightly closed if the day is cloudy or rainy. Petals close in the late afternoon
or early evening (between 4:00 and 6:00 pm). In one study it was determined that
about half of the flowers of a violet wood sorrel patch live for only one day.
The flowers are pollinated by a great variety of bees and other hymenopterans,
lepidopterans and dipterans. Pollinators are attracted to the flowers by sweet
secretions of the nectaries that are located at the bases of the staminal
Human uses of violet wood sorrel have centered on the
application of its acid-rich tissues and fluids to treat medical conditions.
Extracts of the plant tissues and solutions made by brewing and soaking the
leaves and stalks in water have been used to treat mouth ulcerations, stomach
disorders, and urinary tract problems. These preparations have also been used as
appetite stimulators, diuretics, fever reducers, and as treatments for scurvy.