Flower:

Flat clusters (umbels) 1½ to 3 inches across, made up of 7 to 16 groups (umbellets) of up to 20 flowers each. The tiny individual flowers are bright yellow, 1/8 inch across with 5 petals folded inward and 5 yellow stamens.

The central flower in an umbellet is stalkless or nearly so while the rest are stalked. A plant typically has 2 to several clusters, at the top of the stem and arising from upper leaf axils.

Leaves and stems:

Basal and lower stem leaves are heart-shaped, with rounded or blunt tips and long stalks. All leaves have finely toothed edges and are a bit glossy, often with a spot of purple where the leaf or end leaflet meets the stalk.

Higher stem leaves become compound in three leaflets or just deeply three lobed at the base, the leaflets or lobed divisions narrower, lance shaped. Stems and leaves are usually smooth or faintly hairy. Stems are single, or multiples arising from the base.

Fruit:

Fruit is 2-sectioned, oval, slightly flattened, ridged, eventually splitting into 2 seeds.

Seeds are about 3 mm long, elliptic and mature to brown.

Notes:

Very similar to Golden Alexanders (Zizia aurea) which is generally more common, Z. aptera can be distiguished by unlobed or simple basal leaves and upper leaves compound or lobed leaves in threes where Z. aurea's basal leaves are compound in threes and upper compound leaves are typically in multiples of three. Also similar is Yellow Pimpernel (Taenidia integerrima), which has rather airier clusters, toothless leaflets, and the center flower in an umbellet is stalked (only Zizia species have a stalkless flower in the center).