Brassica napus L.

Brassica napus plant

Family - Brassicaceae

Stems - To +80cm tall, bluish-green, glabrous, glaucous, herbaceous, erect, branching above, typically single from base, from taproot.

Leaves - Alternate, sessile, glabrous, glaucous. Basal leaves lyrate-pinnatifid, dentate, to +15cm long. Auricles rounded. Cauline leaves sessile, clasping, auriculate, reduced above, to 9cm long, 3cm broad. Auricles rounded and broad.

Brassica napus leaves

Inflorescence - Terminal racemes, compact in flower and elongating in fruit to +30cm. Pedicels 6-10cm long in flower, elongating in fruit to +3cm and eventually at or near perpendicular to the axis of the inflorescence, glabrous, glaucous.

Flowers - Petals 4, yellow, clawed, glabrous. Claw to 5mm long, pale yellow to whitish. Limb to 5mm long, 4mm broad, rounded to blunt at apex. Stamens 6, 4 larger and 2 smaller (the two smaller stamens opposite and outside of the larger stamens). Filaments to 7mm long, glabrous, yellow-green. Anthers yellow, 2mm long. Ovary glabrous, green, terete, 4-5mm long. Style 1.7mm long, persistent in fruit. Stigma capitate. Sepals 4, 6-7mm long, to 2mm broad, linear, glabrous, yellow-green, erect to spreading, often with revolute margins. Siliques to +6cm long, terete, ascending and almost parallel with the axis of inflorescence, beaked, glabrous. Beak to 9mm long.

Brassica napus calyxCalyx.

Brassica napus flowers

Flowering - April - September.

Habitat - Roadsides, railroads.

Origin - Native to Eurasia.

Other info. - This is the species plant which gives rise to the Rutabaga. Chromosome numbers show that, originally, the plant was a hybrid between B. campestris L. (Turnip) and B. oleracea L. (Cabbage, Broccoli, etc.).
B. napusis not commonly found wild in Missouri but is beginning to spread throughout the state.

Photographs taken off Highway 9, Platte County, MO., 5-2-00.


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