Erysimum repandum L. - Treacle Mustard

Erysimum repandum plant

Family - Brassicaceae

Stems - To +40cm tall, from stout taproot, branching, herbaceous, erect, single or multiple from base, carinate, with appressed pubescence. Hairs of stem bifurcate and oriented parallel to stem axis.

Erysimum repandum stem

Leaves - Early season leaves in basal rosette. Blades to +10cm long and +1cm broad. Tips of basal leaves often curled or hooked. Leaves of stem alternate, gradually reduced upward, coarsely toothed to sub-entire, linear to narrowly oblong, tapering to base, sessile to short petiolate, with bifurcate appressed pubescence above and below.

Erysimum repandum basalsBasal rosette.

Inflorescence - Terminal racemes, sub-compact in flower and elongating in fruit to +25cm long.

Erysimum repandum inflorescence

Flowers - Petals 4, clawed, yellow to bicolored with yellow and white. Claw to 6mm long. Limb of petal 3-4mm long, -2mm broad, glabrous. Stamens 6. Filaments glabrous, whitish, to 6mm long. Anthers -1mm long, greenish-yellow. Ovary to 5mm long, 4-angled, .5mm broad. Style wanting. Sepals 4, distinct, pubescent as stem and leaves, to -6mm long, 1.1mm broad, linear, light green with lighter margins near apex, erect.

Erysimum repandum calyxCalyx close-up.

Erysimum repandum flowerFlower close-up.

Fruit - Siliques to 7.5cm long, 4-angled, widely spreading to erect, with pubescence as stem and leaves, beaked, many seeded. Beak to 4mm long. Pedicels thick, to 5mm long, typically at nearly right angles to axis of stem.

Flowering - April - July.

Habitat - Waste ground, disturbed sites, roadsides, railroads.

Origin - Native to Europe.

Other info. - Still another of the many introduced members of the Brassicaceae! This plant is extremely common and can be found almost anywhere. The flowers can be solid yellow or bicolored as seen above. The taproot can get quite large for the size of the plant, especially if there is not much water near the surface of the ground.

Photographs taken at the Kansas City Zoo, 4-20-00, and at Eagle Bluffs Conservation Area, Boone County, MO., 4-11-04.


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