Kingdom: Plantae

Phylum: Magnoliophyta -- flowering plants

Class: Magnoliopsida -- dicots

Family: Brassicaceae (Cruciferae) -- mustard

Common Name: American wintercress, yellowrocket

Species Code: BAOR

Origin: Native to wet to moist sites in western North America from Alaska south to California and east to New Mexico as well as across most of the northern tier states to New England. Also Eurasia.

Rare: no

Form: forb, biennial or short-lived perennial from a taprooted and sometimes a simple caudex, erect, 20-60 cm tall, glabrous to somewhat hirsute.

Duration: biennial, perennial

Longevity: short

Habitat Type: wetlands, riparian

Wetland Indicator Status: FACW+

Leaves: basal leaves 3-12 cm long, with long petioles, simple or pinnately lobed with 2-6 lateral leaflets, cauline leaves pinnately divided with 5-13 leaflets, auriculate, petiolated below becoming sessile above.

Mature height: 8-24 inches

Flowers: borne in a dense raceme; sepals 2-2.5 mm long, elliptical, yellowish-green; petals 2.5-5 mm long, yellow. Smaller racemes may be borne in the leaf axils.

Flower color: yellow

Bloom: May, June

Bloom starts on: May

Bloom ends on: June

Fruit: silique, 2-5 cm long, 1.5-2.5 mm wide, erect or ascending, slightly compressed; seeds finely pitted, 1.5 mm long.

Characteristics:
Reproduces by seed.
Grows from a caudex or sometimes a taproot.
2n=16.
Flowers are perfect.
Diploids only are known.
Young leaves are edible but become bitter with age.
Fruit is a silique.
Butterfly larva of Stella’s orangetip (Anthocharis stella), cabbage white (Pieris rapae), Becker’s white (Pontia beckerii), western white (Pontia occidentalis), and the large marble (Euchloe ausonides) feed on many species of Brassicaceae (Pocewicz 2005).

Sun requirement: full to partial sun

Soil moisture: wet

Hazards: spreads rapidly along roadside ditches and in moist disturbed areas and may be considered weedy by some.

Sowing time: fall or early spring

Transplant time: No information available

Stratification: cold moist

Seed yield: high

Seed harvest: No information available

Seed cleaning: No information available

Planting duration: short

Seed size: small

Seed harvest date: No information available

Herbaria: Specimen data and digital resources from The Consortium of Pacific Northwest Herbaria

Propagation:
Reproduces by seed.
Seeds need 2-4 weeks of cold moist stratification (Maguire & Overland 1959).

References:
Maguire, James D., and Alvin Overland. 1959. Laboratory Germination of Seeds of Weedy and Native Plants. Washington State Agricultural Experiment Station Circular 349, Pullman, WA. 15 p.

Pocewicz, Amy. 2005. Host Plants of Palouse Butterfly Species. 2 page handout to accompany the April 2005 presentation to the Palouse Prairie Foundation.

Links:
Plant Profile from the USDA PLANTS Database
Species information from the University of Washington Herbarium