Desmodium illinoense aka Illinois Tick Trefoil

Desmodium illinoense belongs to the pea family, Fabaceae. It is a perennial, which means it lives for years. Common names include tick trefoil and Illinois tick trefoil. Its native range runs from southeastern Canada to Arizona. It grows in regions with a temperate climate. In Missouri, it grows in prairies and glades. This upright plant has a slim, rather sparse shape. It suits sites where a loose form fits the scene.

The sources differ on how tall this plant grows. Missouri Botanical Garden gives a usual height of 2–3 feet [0.61–0.91 metres]. Some plants reach 5 feet [1.52 metres], it notes. Chicago Botanic Garden gives 3–6 feet [0.91–1.83 metres]. Plants can spread to about 2 feet [0.61 metres]. Hairy stems lack branches and bear trifoliolate leaves. This means each leaf has three leaflets. A clear net of veins shows beneath each leaflet. Hooked hairs cover these lower faces, too. Clear, easy-to-see stipules sit at the leaf stalk bases.

Loose, narrow groups of flowers grow at the stem tips. The pea-like blooms range from white to pink. Chicago Botanic Garden gives July through August as bloom time. Missouri Botanical Garden calls the blooms showy and white. Flat seed pods form once the blooms fade. Each pod has three to seven parts, or segments. A dense coat of tiny hooked hairs covers the pods. The hooks catch on hair and clothes. This makes the pods a drawback near paths or borders.

Grow this plant in full sun. Give it dry soil or soil with a moderate amount of moisture. Chicago Botanic Garden lists part shade as suitable, too. It grows well in average garden soil. It copes with drought and needs little routine care. Chicago lists it for USDA zones 4–7. Like other legumes, it hosts rhizobia at its roots. These helpful bacteria live in close contact with its roots.

Use Illinois tick trefoil in native gardens, meadows, or prairie plantings. It also suits sites where plants can spread on their own. When the site suits it, it grows freely from its own seed. Missouri Botanical Garden finds it somewhat weedy for borders. Chicago warns that sandy soil can make it spread with force. Allow for this spread when you choose its place. Missouri Botanical Garden reports no serious insect or disease problems. The sources do not show whether humans can eat it. Nor do they show whether it is toxic.