Oxalis stricta

Native

Dry. Prairies, disturbed sites.

May–October

Yellow

6″ to 24″

This is an 6″ to 24″, but usually 6″ to 12″ tall, usually erect, sometimes lying flat on the ground, bushy, perennial forb rising on a central, branching stem from a long, slender rhizome.

The stems are hairy.

The leaves are alternate and on long leaf stalks. They are palmately divided into three leaflets.

The leaflets are ⅜″ to ¾″ wide and inversely heart-shaped with the attachment at the narrow end. They are gray-green or green and usually hairless, but sometimes have a fringe of hairs along the margin. The margins are untoothed. The leaflets open and spread outwards during the day. They fold closed along the midrib and droop downward at night. They also close under intense sunlight. They repel water, so that after a rain they look dry with water beads on the surface.

The inflorescence is an umbrella-like cluster of 2 to 7 flowers usually held below the leaves. The clusters branch when they age.

The flowers are about ½″ wide on long flower stalks that position them above the leaves. They have 5 petals and 5 much shorter sepals which are visible between the petals. Like the leaves, they close at night.

The fruit is a ⅓″ to ½″ capsule held on an erect, unbent stalk.

Southern yellow wood sorrel (Oxalis dillenii) does not grow from a rhizome. The umbrella-like flower cluster is not branched. The fruit is a ½″ to 1″ capsule held on an erect, unbent stalk.