Flower:

Dense spikes 1 to 4 inches long of small, conical flowers set in a tight spiral, with 5 flowers completing one turn of the stem; about 18 flowers per 1/3 inch of spike. Flowers lack petals but are formed by a calyx densely covered in woolly hairs that has a small creamy colored star-shaped opening at the tip with an orange-brown center. Inside the tube is a column of stamens and a single style. Flowers bloom from the bottom of the spike up, a spike growing to a length of 3 to 4 inches at maturity but earlier blooms fall from the stalk as they mature. A plant typically has a few to several spikes on a few branching stems, often with 1 to 4 spikes along the stem, the largest spike at the tip of the stem; the terminal spikes typically become nodding.

Leaves and stem:

Leaves are opposite, restricted to about the lower third of the plant, 2 to 5 inches long, ½ to 1 inch wide, lance elliptic, toothless, pointed or blunt at the tip, with or without a leaf stalk, silky hairy, often covered by fine, cobwebby hairs when young. Stems are stiff and erect, somewhat quadrangular and covered with fine flattened hairs to downy, longer hairs. Hairs are gray, white or brown.

Fruit:

A 1-seeded fruit develops inside the persistent calyx tube, the woolly hairs unfurling as the seed matures, the entire structure eventually dropping off.

Notes:

Prairie Cottonweed is only found on some of our sandiest soils. As an annual, the plant's characteristics change with age, early plants are more compact and covered by fine hairs and the flower spikes are short and erect. Older plants lose the fine longer hairs in their leaves and the spike becomes elongated, weighing the stem down so that it nods to one side.