Brassica rapa L.
turnip, rape

Annual or biennial herbs with slender or stout tuberous taproots. Basal leaves lyrate-pinnatisect, upper stem leaves simple, obovate-oblong, almost cordate at the base, sessile, glabrous or nearly so. Racemes dense in flower, the open flowers generally overtopping the buds; lax in fruit. Flowers yellow, petals 6–10 mm long. Many forms have been in cultivation for centuries and the origin of the species is obscure. The different cultivars vary in colour and size of the seeds and in leaf shape and size. This species is naturalised in South Africa where it is widely distributed in Limpopo, Gauteng, Mpumalanga, Free State and the Eastern, Northern and Western Cape.

Brassica juncea (L.) Czern. & Coss.
Chinese mustard

Annual herbs up to 1 m high, with slender ascending branches. Stem hispid near the base but glabrous above. Lower leaves lyrate-pinnatisect, with 1 or 2 pairs of small, broad, lateral lobes and a large, ovate or obovate terminal lobe. Upper leaves are glabrous, smaller, simple, entire or dentate, shortly petiolate. Racemes terminal, dense in flower, lax in fruit. Flowers yellow, petals obovate, 7–9 mm long, almost 3 mm broad, shortly clawed. The fruiting pedicel is slender. Seeds globose, 16–24, brown, in one row. The seed coat is reticulately pitted. Native of southern and eastern Asia. Widespread as an established weed in the tropics and subtropics and as a casual weed in many parts of Europe and in the Eastern Cape, Free State, KwaZulu-Natal, Limpopo and the Western Cape in South Africa.

Brassica napus L.
rapeseed, canola

This is a bright yellow flowering member of the Brassicaceae. It is cultivated mainly for its oil-rich seed, the third largest source of vegetable oil in the world, and is also consumed as a vegetable in China. Wild forms of B. napus have been reported to occur on the beaches of Gothland, Sweden, the Netherlands and Britain. It is thought that B. napus is a hybrid of B. oleracea and B. rapa, the wild species found on the coast of northern Europe.