Ambrosia trifida L. - Giant Ragweed

Family - Asteraceae

Stems - No info. yet.

Leaves - No info. yet.

Inflorescence - No info. yet.

Flowers - No info. yet.

Flowers close-up.

Flowering - July - September.

Habitat - Low woods, along streams, pond margins, waste ground, roadsides, railroads.

Origin - Native to U.S.

Other info. - A. trifida is found throughout Missouri and is the most abundant member of the genus in this state. It is very prolific and forms huge colonies when left undisturbed.
According to Steyermark there are 2 varieties of A. trifida in Missouri. Variety trifida f. integrifolia (Muhl.) Fern. has leaves which are unlobed, form trifida has typical 3-lobed leaves with a winged petiole. Variety texana Scheele has petioles with no wing.

Photographs taken at the Sunklands Conservation Area, Shannon County, MO., 8-1-04.