Go to Midwest Weeds and Wildflowers Home Page

Horseweed, Mare's tail, Canada Horseweed

[Conyza canadensis (L.) Cronq.]

Asteraceae (Sunflower Family)

▲ ▼ young plants

▲ ▼ young plants

 

▲ ▼ young plants

▲ ▼ young plants

 

▲ ▼ mature plants

▲ ▼ flowering plants

 

▲ ▼ flowering plants

▲ ▼ flowering plants

 

▲▼ flowering upper portion of plant 

▲ flower detail

▲ vacant lot with many mature plants

▲ prairie restoration with many horseweed plants near its border

▲▼mature, flowering and post-flowering plants starting to release seeds

▲▼drying, post-flowering plants in the autumn

 

Conyza canadensis (L.) Cronq., Horseweed, Marestail:  (Bayer Code:  ERICA; US Code COCA5)

·         U.S. native summer annual that grows 2-7 feet tall

·         Usually unbranched (unless mowed or grazed), and stems and leaves are covered with fine hairs that stand out from the stems/leaves

·         Leaves alternate, lanceolate, narrow, with a few teeth along the margins and a pointed tip; leaves often look wilted or droopy, particularly in heat of summer or on warm, windy days

·         A large, much-branched panicle of small, white flower heads is produced at the top of stems; head flowers don’t open very much

·         After flowering, white pappus (“parachutes”) emerge from flower heads to carry attached seed in the wind

·         Horseweed may be allelopathic—where it is established, little else grows

·         Several populations have been indentified  in U.S. that are resistant to common herbicides

·         Is invasive; reproduces rapidly by seed

·         Grows in cultivated fields, pastures, urban areas

Go to Midwest Weeds and Wildflowers Home Page