Virginia Tech Weed Identification Guide

Hairy Bittercress: Cardamine hirsuta

Hbittercress3-21b.jpg (165987 bytes) Weed Description: Most often a summer annual but occasionally a winter annual weed of landscapes, container-grown plants, and greenhouses.  Hairy bittercress is found throughout the northern half as well as the southeastern United States.

Seedlings:   Cotyledons are round and occur on petioles.  Cotyledons and first true leaves have hairs.  Subsequent leaves consist of alternately arranged leaflets.

Stems:  Erect, branched at the base, reaching as much as 12 inches in height.

Roots:  A taproot.

Leaves:  Leaves consist of 2 to 4 pairs of leaflets that are arranged alternately along the central leaf stem.   Individual leaflets are round in outline.  Each leaf occurs on a petiole that is usually distinctly hairy.  Lower leaves may be hairy but not as distinctly hairy as the upper leaves.  Upper leaves are smaller than the lower basal leaves.

Flowers:  Occur in clusters at the ends of the flowering stems.  Individual flowers are small (2-3 mm) and consist of 4 white petals.

Fruit:  A silique, which is a long (3/4 to 1 1/4 inches), narrow capsule with many seeds.  Siliques explosively spread the seed as much as 10 feet from the parent plant.

bitrcress4-8.jpg (55665 bytes)
Identifying Characteristics:   The long narrow siliques and round leaflets that are arranged alternately are both characteristics that help in the identification of hairy bittercress.  This plant might be confused with Calepina (Calepina irregularis), however calepina does not have 2 to 4 pairs of round leaflets like hairy bittercress.