Desmodium canadense (L.) DC. - Beggar's Lice, Tick Trefoil

Desmodium canadense plant

Family - Fabaceae

Stems - To +2m tall, herbaceous, erect, pubescent, with vertical striations.

Desmodium canadense stem

Leaves - Alternate, trifoliolate, petiolate, stipulate. Leaflets 3.5-14cm long, ovate to lanceolate, obtuse or short pointed at tip, appressed pubescent above, pilose below. Stipules to 1cm long, pubescent, lanceolate, striate.

Desmodium canadense leaves

Inflorescence - Terminal racemes or panicles to +40cm long.

Desmodium canadense inflorescencePortion of the inflorescence.

Flowers - Papilionaceous, pink to rose, +/-1cm long. Standard with two yellow spots at base. Stamens diadelphous. Calyx bilabiate, short-tubular. Loments rounded to slightly angled on the ventral margin, rounded on dorsal margin, typically 4-6-jointed, pubescent, to 7mm long, 5mm wide.

Desmodium canadense calyxCalyx.

Desmodium canadense flower

Flowering - July - September.

Habitat - Prairies, thickets, wet meadows, lake margins, roadsides, railroads.

Origin - Native to U.S.

Other info. - This tall, weedy species can be found scattered throughout most of Missouri. It can be identified by its large size, large flowers, pubescent stems and leaves, and lanceolate leaflets.
Many plants from this genus are similar, D. canadense is typically more robust than any other species in Missouri. It has dense, large racemes and panicles also.

Photographs taken off Hwy H, Shannon County, MO., 8-10-03 & 7-30-04.


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