Little bittercress  (Cardamine oligosperma)

Little bittercress is a winter or summer annual (and sometimes biennial) broadleaf. In California, it is considered a desirable floral community member in natural settings, but is sometimes weedy in disturbed places such as landscaped areas, orchards, nurseries, turf, and vegetable crops. Little bittercress is found up to an elevation of about 2600 feet (800 m) in the Klamath Ranges, North Coast Ranges, San Francisco Bay region, Sacramento Valley, and likely other California areas, as its range is expanding.

Seedling

Cotyledons (seed leaves) are egg shaped to nearly round, with slightly indented tips and stalks. Leaves alternate along the stem. The first one to three leaves are semicircular to kidney shaped, with sparse coarse hairs, and have stalks that are as long as, or longer than the leaf blades.

Mature plant

Plants range from 3 to 12 inches (7.5–30 cm) tall, with several branched, smooth stems emerging from the soil line. Leaves radiate from the base of the stem, forming a rosette. Leaves divide into two to five lateral leaflet pairs, and one larger terminal leaflet. Leaflets of rosette leaves are often round to kidney shaped. The upper stem leaflets are narrower than those near base. Leaflet edges are smooth to slightly lobed. Hairy bittercress, C. hirsute, is similar but with fewer, lobed or kidney-shaped leaflets.

Flowers

Flowers bloom from March through July. Two to ten white flowers are found along the stem on stalks of unequal length.

Fruits

Narrow pods, 1/2 to 3/4 inch (1.3–1.9 cm) long, split open into two curling valvelike structures. When mature, pods explosively project seed to several yards (meters) away.

Reproduction

Little bittercress reproduces by seed.

Seeds

Seeds are flattened and finely pebbled.

Related or similar plants

• Hairy bittercress, Cardamine hirsuta

More information

• Broadleaf ID illustration
• Calflora’s distribution map for landscape information
• For agriculture: UC IPM Pest Management Guidelines