Flower:

Loose branching clusters at the top of the plant, each branch with several whorls of 4 to 8 slender-stalked flowers, with separate male and female flowers on the same or separate plants. Flowers are about 1/8 inch long, green to pink to reddish, 3-sided with 2 series of tepals (petals and similar sepals). The outer tepals are much smaller than the inner and strongly bent back (reflexed). The 3 inner tepals are heart-shaped to triangular with rounded angles, distinct venation across the surface and broad, papery wings that are somewhat wavy along the edge. At the base of each inner tepal is a projection called a grain, very narrow and about half as long as the tepal, often obscure and may be absent altogether. Tepals are slightly spreading and close up after pollination. Flower stalks are very slender and smooth.

Leaves and stems:

Leaves are mostly basal, up to 5 inches long and 1½ inches wide, lance-oblong, blunt to pointed at the tip, with a pair of downward pointing lobes at the base (sagitate), on a long stalk, becoming smaller and stalkless with somewhat clasping bases as they ascend the stem. Edges are toothless and may be slightly wavy, surfaces are hairless.

At the base of the leaf stalk is a brownish papery sheath (ocrea) that surrounds the stem. Stems are erect, unbranched except in the flower clusters, ribbed and hairless.

Fruit:

A flower produces a single seed, wrapped in the persistent tepals which form a capsule-like structure. Seeds are 3-sided, oval-elliptic with an abrupt taper to a short beak at the tip, dark brown, and about 2 mm long.

Notes:

An uncommon introduction in Minnesota, Green Sorrel may be mistaken for the ubiquitous Common Sheep Sorrel (Rumex acetosella), which has flowers and fruits about half the size of Green Sorrel, lacking wings on the tepals, and has smaller leaves with a pair of basal lobes that extend outward (hastate), not down (sagitate).