Virginia Tech Weed Identification Guide

Tick Trefoil: Desmodium viridiflorum

Weed Description:  Erect perennial with trifoliate leaves that may reach 6 1/2 feet in height.  Primarily a weed of pastures, roadsides, and noncroplands that is found throughout the southeastern United States and as far North as eastern Pennsylvania and southern New York.
Leaves: Occur in clusters of 3 (trifoliate leaves).  Individual leaflets are ovate in outline, approximately 1 to 3 1/2 inches long, roughly hairy above and densely velvet hairy below.  Distinctive lance-shaped stipules also occur at the base of the leaf petioles where they meet the stem.
trefoil9-10.jpg (44326 bytes) Stems:  Erect, branching, hairy, reaching 6 1/2 feet in height.
Flowers: Occur in elongated inflorescences where each flower arises from a central stalk (racemes).  Individual flowers occur on flower stalks (pedicels) that are from 2 1/2 to 8 mm long.  Flowers are pink to purplish in color and are approximately 5 to 9 mm long.
Fruit: A loment of 2 to 6 segments that are each triangular in outline.

Identifying Characteristics:  A large, erect perennial with trifoliate leaves, stipules, and relatively small pink or purple flowers.  There are many different 'tick trefoil' species and their primary identifying characteristics are trifoliate leaves, presence of stipules, and loments.