Common Wood Sorrel (also known as Sour Grass, Sheep's Clover)
Kingdom: Plantae, Division: Tracheophyta, Class: Magnoliopsida, Order: Oxalidales, Family: Oxalidaceae, Genus: Oxalis, Species: Oxalis acetosella · Oxalidaceae (Wood Sorrel family) · Compound (trifoliate with three heart-shaped leaflets), deciduous
Species
Oxalis acetosella
Leaf Type
Compound (trifoliate with three heart-shaped leaflets), deciduous
Family
Oxalidaceae (Wood Sorrel family)
Shape
Obcordate (heart-shaped leaflets with notched tips)
Size
Each leaflet is approximately 0.5 to 1 inch wide; the entire leaf cluster spans about 1.5 to 2 inches, typical for the species
Margin
Entire (smooth)
Arrangement
Basal rosette arising directly from an underground rhizome
Rarity
Common
Color & Pattern
Vibrant medium to bright green upper surface with slightly paler undersides; occasionally exhibits faint purple-red tints on the lower surfaces
Venation Pattern
Palmate venation branching from the base of each leaflet
Texture & Surface
Soft, delicate, and glabrous (smooth) with a matte finish
Description
A low-growing, delicate perennial herb featuring thin, creeping rhizomes and unmistakable clover-like leaves composed of three heart-shaped leaflets that fold down at night or in strong sunlight. It produces dainty white or pale pink flowers with delicate purple striping during spring and early summer.
Key Features
Distinctive heart-shaped leaflets arranged in threes that fold in response to light levels, sour-tasting sap, and delicate white-pink bell-shaped flowers
Habitat
Shaded woodlands, forest floors, acidic soils, and damp, cool environments with partial to full shade
Geographic Range
Native to temperate regions of Europe, Asia, and parts of North America
Condition Notes
The leaf appears healthy, turgid, and vibrant green with no visible signs of insect damage, disease, or nutrient deficiency. Grade: Excellent
Interesting Facts
The name 'acetosella' comes from the Latin word for sour, referring to the characteristic tangy flavor caused by oxalic acid. The leaflets exhibit nyctinasty, folding downwards at night or during dark, overcast weather to protect themselves.
Medicinal & Uses
Traditionally used to add a pleasant, tart lemon-like flavor to salads and beverages. Historically used in herbal remedies to reduce fevers and aid digestion, though excessive consumption should be avoided due to oxalic acid content.
Ecological Role
Provides ground cover in forest ecosystems, helps retain soil moisture, and offers food sources for small woodland herbivores and insects
Similar Species
White Clover (Trifolium repens) or Black Medic (Medicago lupulina), which have rounded or oval leaflets with fine teeth along the margins, unlike the smooth, heart-shaped leaflets of Wood Sorrel.
Foraging Tips
Look for cool, shaded forest floors under canopy trees during spring and summer. Companion plants often include mosses, ferns, and shade-loving perennials. Taste a small piece of a leaflet to confirm the distinct tartness.
Toxicity Warning
Mildly Toxic due to high levels of oxalic acid. While safe in small culinary amounts as a garnish, large quantities can bind calcium and are potentially harmful, especially for individuals with kidney stones, gout, or arthritis.