Brassica napus L.



CC = *
CW = 5
MOC = 10

© DETenaglia

Family - Brassicaceae

Habit - Annual or biennial forb, from often fleshy and expanded taproot.

Stems - Erect, to 1.5 m, sometimes branching, often reddish below, glabrous, glaucous.

Brassica_napus_root.jpg Fleshy root.

© DETenaglia


© SRTurner

Brassica_napus_stem2.jpg Stem and leaf base.

© SRTurner

Leaves - Basal and lower leaves often absent at flowering, 5-25 cm long, irregularly pinnately divided or lobed, petiolate but sometimes with rounded auricles at the base, mostly obovate in outline. Stem leaves alternate, glabrous, glaucous, progressively reduced toward the tip, the uppermost 2-5 cm long, sessile, the bases clasping and with rounded auricles of tissue, linear to narrowly oblanceolate in outline, irregularly toothed or shallowly lobed.

Brassica_napus_leaf2.jpg Leaf abaxial.

© SRTurner

Inflorescences - Terminal racemes, compact in flower, elongating in fruit. Pedicels of flowers 5-6 mm long, elongating in fruit to 1.5 cm, 1 mm in diameter, not subtended by bracts.

Brassica_napus_inflorescence.jpg Inflorescence.

© SRTurner

Flowers - Sepals 4, 6-10 mm long, yellow, glabrous, linear, spreading to erect. Petals 4, 1.0-1.6 cm long, 4-5 mm broad at apex, yellow, glabrous, to 1cm long, clawed. Stamens 6, erect. Longer 4 stamens with filaments to 4.5 mm, white, glabrous. Shorter stamens with filaments to 2 mm. Anthers yellow, 2 mm long. Ovary 4.5 mm long, slightly flattened, glabrous. Style 2 mm long, persistent in fruit as beak.

Brassica_napus_calyx.jpg Calyx.

© DETenaglia

Brassica_napus_flower.jpg Flowers.

© DETenaglia

Brassica_napus_flower2.jpg Lateral view.

© SRTurner

Brassica_napus_flower3.jpg Frontal view.

© SRTurner

Fruits - 5.0-9.5 cm long, more than 10 times longer than wide, ascending or spreading, terete or nearly so, the slender, tapered beak 9-15 mm long. Seeds 1 row per locule, 24-40 per fruit, globose, 1.5-2.5 mm in diameter.

Brassica_napus_fruit.jpg Fruits.

© SRTurner

Flowering - April - September.

Habitat - Cultivated and escaped to waste places, roadsides, railroads.

Origin - Native to Europe.

Lookalikes - Other members of the Brassica genus. In particular, confident differentiation from Brassica rapa can be very difficult.

Other info. - This is the commonly cultivated rutabaga long used by humans as a root and storage vegetable. The plant is actually quite nice to look at. Its occurrence in Missouri is sporadic, uncommon, and waiflike, except where cultivated. Escapes do not seem to persist long in the wild. Identifying features include glabrous and glaucous herbage, leaves with clasping bases, and relatively large, bright yellow flowers.

Brassica napus originated from past hybridization between B. oleracea and B. rapa, and can be difficult to distinguish from the latter parent. Some botanists have subdivided the species based on differences in the rootstocks, though populations persisting in the wild tend to lose these differences. Forms of the plant lacking a thickened rootstock (var. napus) are known as rape or rapeseed, the seeds of which are the source of canola cooking oil. Canola oil is thought to be a relatively healthy fat due to its fatty acid composition, and rapeseed is becoming increasingly important as a commercial crop. Sightings of the plant as escapes from cultivation may therefore become more frequent with time.

Turnips (rootstocks of B. rapa L.) resemble rutabagas but the roots are flat across the top.

Photographs taken off Hwy 29, Pike County, AL., 2-26-05; also near Labadie, Franklin County, MO, 4-21-016, and at Silver Mines Recreation Area, Madison County, MO, 4-8-2019 (SRTurner).