Brassica napus subsp. napus
Annual or biennial, 30-150 cm tall, erect, branched, ± glabrous, glaucous; tap root about as thick as the stem, slender. Lower leaves often lyrate-pinnatisect, 5-25 cm long, 2-6 cm broad (rarely larger), sub-bijugate, stalked; terminal lobe largest, ovate, rounded at the apex, broadly crenate or dentate, subtruncate at the base; lateral lobes smaller, ovate; middle and upper leaves becoming gradually lanceolate, ± entire with a broadened cordate base clasping at least 1/2 of the stem, apex acute; all leaves glaucous. Racemes 15-40-flowered, laxly corymbose with buds overtopping the opened flowers. Flowers 10-15 mm across, pale yellow; pedicel 6-12 mm long, increasing up to 20 mm (rarely more) in fruit, spreading. Sepals 5-8 mm long, 1.5-2 mm broad, erect, glabrous, subequal. Petals 10-15 mm long, 3.5-6 mm broad, obovate, narrowed towards the base. Stamens 5-7: 7-9 mm long. Siliquae 40-80 (-100) mm long, 2.5-4 mm broad, linear, subtorulose, including a beak about half as long as the entire pod and usually 0-1 seeded, glabrous; valve with a prominent mid-vein; stipe rarely present; septum memb¬ranous, not veined; seeds 10-20 (rarely more) in each locule, globose, about 1.5 mm in diam., yellowish-brown, often blackish near the hilum, finely reticulate¬alveolate.
Type: Described from Europe: England etc.
Distribution: Widespread throughout the temperate regions of the world and widely introduced. Original home not definitely known and perhaps nowhere occurs in wild form.
‘Rape group’ includes Colza etc. and seeds contain about 40% oil which dries slowly.
Herbarium specimens are very much lacking due to the tendency of plant collectors to overlook the cultivated plants. The other two varieties of this subsp., var. quadrivalvis (Hook. f. et Thoms) O.E. Schulz (B. quadrivalvis Hook. f. et Thorns in J. Linn. Soc. Bot. 5: 170, 1961) and var. trilocularis (Roxb.) O.E. Schulz, l.c. (Sinapis trilocularis Roxb., Fl. Ind., 3:121, 1832; B. trilocularis (Roxb.) Hook. f. et Thoms., l.c.) are recorded from India but I have not yet seen any specimen of these from our area.