Virginia Tech Weed Identification Guide

Marijuana: Cannabis sativa

Weed Description:  Annual weed with distinctive leaves and odor that may reach 10 feet in height.  Found throughout the United States except in the southwest and northern Great Plains.

Seedling: Cotyledons egg-shaped, without hairs.  First true leaves are opposite and have distinctly serrated   margins.

Leaves:  Lower leaves are opposite, upper ones are alternate.  All leaves are divided into 5 to 9 leaflets that each arise from a common point (palmately divided).  Individual leaflets have serrated margins and are hairy.

Stem: Rough to the touch, hairy, somewhat grooved, and branched.  Hairs along the stem exude a sap that contributes to the distinctive smell of this plant.

Roots:   Taproot.

Flowers:   Male and female flowers are produced on separate plants (dioecious).  Male flowers arise from the position between the stem and the leaf (leaf axils) and are elongated inflorescences in which each stalked flower arises from a central stem (racemes).  Female flowers also arise from the leaf axils, but are spikelike clusters.

Fruit: An achene that is approximately 4 mm long, oval in shape, and yellow to brown in color.

Identifying Characteristics: The 5 to 9 distinctive leaflets with serrated margins that arise from a common point and the characteristic smell of marijuana help to distinguish this plant from most other weeds.  The leaflets of some of the cinquefoils like Sulfur Cinquefoil (Potentilla recta) closely resemble those of marijuana, however the individual leaflets of the cinquefoils are much shorter than those of marijuana, and these plants also have a prostrate growth habit unlike that of marijuana.