Cardamine douglassii Britton

Purple Cress


CC = 9
CW = -3
MOC = 12

© DETenaglia

Family - Brassicaceae

Habit - Perennial forb with short, tuberous, unsegmented rhizomes.

Stems - Ascending to erect, to 30 cm, terete, simple or sparsely branched in the apical half, with spreading hairs 0.3-0.6 mm long, especially in the apical half.


© DETenaglia

Leaves - Alternate, petiolate below, becoming sessile above, 2-7 cm long, simple, entire, wavy-margined, or with few, shallow, widely spaced teeth, often sparsely hairy; the basal leaves usually withered by flowering time, long-petiolate, the leaf blades ovate to cordate; the stem leaves mostly 3-5, mostly sessile, ovate to lanceolate or narrowly elliptic.

Cardamine_douglassii_leaves.jpg Pressed leaves.

© DETenaglia

Inflorescence - Terminal raceme, compact in flower, quickly elongating in fruit up to 15 cm. Axis mostly glabrous. Pedicels ascending, to 2.5 cm in fruit, glabrous.

Cardamine_douglassii_inflorescence.jpg Inflorescence.

© DETenaglia

Flowers - Sepals 4, 3.0-6.0 mm long, reddish purple. Petals 4, 8-14 mm long, pink to purplish pink. Styles 3-4 mm long.

Cardamine_douglassii_calyx.jpg Calyx.

© DETenaglia

Cardamine_douglassii_flower.jpg Flower.

© DETenaglia

Fruits - Siliques 25-40 mm long, sometimes aborting before maturity, 2-valved, with a beak to 4mm long, slightly constricted between the seeds. Seeds 1.7-2.1 mm long, irregularly oblong to circular in outline, the surface slightly roughened, orange to greenish yellow.

Cardamine_douglassii_fruit.jpg Developing fruit.

© DETenaglia

Flowering - March - April.

Habitat - Mesic or bottomland forests.

Origin - Native to the U.S.

Lookalikes - C. bulbosa.

Other info. - This attractive species can be found mainly in a handful of counties in the northeastern corner of Missouri. The plant can be identified by its reniform basal leaf blades, sessile cauline leaves, and big flowers. The flowers are typically pink to purple but the plants photographed in Columbia, MO., had white flowers. The upper stems usually bear short, spreading hairs which further serve to differentiate this species from the closely related C. bulbosa.

Photographs taken off the MKT Trail, Columbia, MO., 4-15-04 (DETenaglia).