Flower:

Numerous tiny flowers are tightly packed in round clusters (glomerules) less than 1/8 inch diameter in a spike-like arrangement at the top of the stem and along stalks up to 4 inches long arising from leaf axils. Flowers lack petals, have 1 to 3 short stamens and an oval, green ovary with a 2-parted style at the tip. Cupping the flower is a green calyx with usually 3 rounded lobes less than 1 mm long, sometimes 4 lobes.

Bracts are leaf-like but may be absent especially on the upper half or more of a spike. The calyx and stalks are smooth and hairless; bracts may be mealy-white especially on the underside.

Leaves and stems:

Leaves are alternate, typically ½ to 2 inches long, up to about ½ inch wide, egg-shaped to oblong in outline, with 2 to 4 shallow lobes or large teeth on each side, the lobes/teeth rounded to pointed, the leaf tip also rounded to pointed, the base wedge-shaped tapering to a short stalk.

Surfaces are hairless, the upper surface smooth or sparsely white-mealy with the underside densely white-mealy. Color is typically blue-green. Stems are branched from the base, erect or more often prostrate from the base, green to red or red striped, may be white-mealy especially towards the base but typically smooth on the upper stem.

Fruit:

Fruit is a dry seed enclosed in the persistent ovary shell (pericarp) that matures from green to brown and loosely wraps the seed. Fruit in the glomerule is mostly arranged horizontally with some vertical. Seeds are flattened oval to round, up to 1.1 mm long, shiny dark reddish-brown with a wrinkled and pitted texture.

Notes:

Oak-leaved Goosefoot, known in some references as Oxybasis glauca, is an annual found mostly in disturbed soils such as gravel pits, empty lots, dumps, river banks, marly, sandy or gravelly shores, and the occasional garden. It is distinguished from other Chenopodium species by leaves that are typically small, lance-oblong in outline with a few shallow lobes or large teeth around the edges, usually blue-green in color, and densely white-mealy on the underside. The flower or fruit clusters are not white-mealy, and the calyx has only 3(4) lobes. There are two recognized varieties, both of which have been found in Minnesota: var. glauca is of European origin, lacks leaf-like bracts in the flower clusters and has rounded teeth/lobes on leaves; var. salinum is native to North America, has leaf-like bracts throughout the flower clusters and has pointed teeth/lobes on leaves.

It is one of the easier Chenopodium species to identify. By comparison, other species may have leaves that are more deeply lobed or not lobed at all, not white-mealy on the underside, are white-mealy in the flower and fruit clusters, have 5 calyx lobes, and/or seeds have a smooth surface. Of note is that, while the leaves of Oak-leaved Goosefoot are typically small and the plant rather sprawling, in cultivation it can be quite robust with more erect stems and larger leaves.