Horseweed (marestail) – Conyza canadensis

Horseweed (marestail) – Conyza canadensis

Conyza canadensis (L.) Cronq.

Asteraceae (Aster family)

MI Status

Native

Life cycle

Erect winter or summer annual.

Leaves

Cotyledons are egg- to spatula-shaped and hairless. Seedling leaves initially develop from a basal rosette; mature leaves are alternate and numerous, and crowded along an erect central stem. Leaves are hairy and linear to lance-shaped with smooth to toothed margins, gradually becoming smaller toward the top of the plant.

Stems

Erect, hairy central stem arises from a basal rosette, then branches to flower, reaching up to 7 feet tall. Flowering branches resemble a horse’s tail.

Flowers and fruit

Numerous clusters of small, white flower heads are found on many short branches near the top. Each seedhead is capable of producing thousands of small seeds; each seed is enclosed in a single-seeded, wind-disseminated fruit.

Reproduction

Seeds.

Accessibility Questions:

For questions about accessibility and/or if you need additional accommodations for a specific document, please send an email to ANR Communications & Marketing at anrcommunications@anr.msu.edu.

Plant & Pest Diagnostics