A biennial plant producing a large leafy rosette the first year and a single leafy seed stalk with short branches on top third of the plant the second year. Produces a thick woody taproot that can reach several feet in length. Leaves are dark green, 6 or 7 inches long by 2 inches wide, alternate and clasping and softly pubescent. Flowering begins by late June. Flowers are reddish purple forming at branch ends. Seeds form in a cluster of four nutlets, breaking apart at maturity, each covered in stiff fine spikes that are curved at the tip. This Velcro characteristic allows the seed to tenaciously cling to fabric and animal hair. Seeds are carried by animals for many miles from the mother plant. Seeds can remain viable for up to 20 years, however they rarely persist more than 3 years. At maturity crushed foliage emits a musty or moldy odor. Moderately toxic, can cause irreversible liver damage, mortality may be delayed.

Houndtongue is a biennial plant and only reproduces by seed. Stopping seed production is essential to control. Every effort should be made to avoid mature patches and to remove any seed capsules from pets and yourself. It is wise to collect and destroy removed capsules by fore or bagging and sending to a landfill. No biocontrol insects are currently available. As with all biennial plants, herbicides much better and at lower rates in the first year of the two year cycle. It is difficult to find a herbicide that has houndstongue on the label, but there are very effective products on the market.