Flower:

Branching clusters at the top of the plant, each branch with numerous whorls of 10 to 20 slender-stalked flowers, usually crowded towards the branch tips and more widely separated below. Flowers are about 1/4 inch long (5 to 6 mm), light green to pinkish, 3-sided with 2 series of tepals (petals and similar sepals) and the outer tepals much smaller than the inner. The 3 inner tepals, also called valves, are mostly round to heart to kidney-shaped, distinctly veined across the surface, the edges mostly flat and slightly jagged. The base of the midvein of each inner tepal is slightly swollen, occasionally producing a protrusion called a grain. Tepals are spreading at flowering time, revealing stamens and styles, and close up after pollination. Flower stalks are very slender and smooth, a little longer than the inner tepals at flowering time, with a distinct, swollen joint in the lower third.

Leaves and stems:

Leaves are both basal and alternate, hairless though sometimes rough along the veins on the underside, toothless to scalloped around the edge and crinkly-wavy, the base wedge-shaped to straight across to somewhat heart-shaped. Basal leaves are oblong-elliptic, 10 to 20 inches long and 2½ to 6 inches wide, on a stalk about as long as the blade.

Stem leaves are somewhat smaller and shorter stalked than basal leaves. At the base of the leaf stalk is a brownish papery sheath (ocrea) that surrounds the stem and mostly disintegrates with maturity. Stems are stout, erect, mostly 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 and dry to rusty brown.

Seeds are 3-sided, elliptic, dark brown to reddish brown, and 3 to 3.5 mm long.

Notes:

Dooryard Dock is an uncommon weed of roadsides, farm fields, and waste areas but is likely under-reported in Minnesota. There are at least 11 similar Rumex species in the state, 5 of which are native. Some of the distinguishing characteristics are whether the leaves are crinkly-wavy or relatively flat, the shape of the inner tepals at maturity, size and shape of the grains, whether the grains on all 3 inner tepals are about the same size, sometimes the length of the flower stalk, or where the stalk is jointed, or the vein pattern on the leaves. Dooryard Dock has crinkly-wavy leaves, tepals up to 6 mm long that are kidney-shaped to nearly round and only slightly ragged around the edge, usually no significant grains (rarely a single one), and the flower stalk has a swollen joint in the lower third.

Of the other docks with crinkled-wavy leaves, the most common by far is Curly Dock (Rumex crispus), which has smaller, narrower leaves, narrower and more egg-shaped tepals, and at least one tepal has a distinct grain. Narrowleaf Dock (Rumex stenophyllus) has narrower leaves and distinctly toothed inner tepals, each with a grain. Field Dock (Rumex pseudonatronatus) also has no grains, but has much narrower leaves and tepals about half as wide. Great Water Dock (Rumex britannica), a native wetland species, has basal leaves that are more or less flat, 3 grains that are all about the same size and shape. Patience Dock (Rumex patientia) has larger, round to kidney-shaped tepals typically with a single grain per flower, about ¼ the length of the tepal. Bitter Dock (Rumex obtusifolius) has broad, heart-shaped basal leaves and tepals with a few large teeth around the edge.

We suspect some of these non-native species are under-reported in the state, largely ignored because they're all assumed to be Curly Dock.