Field Mustard (Brassica rapa)

Brassica rapa, field mustard, is an herbaceous annual or biennial species in the Brassicaceae (the cabbage or mustard family) from which various interrelated vegetable varieties have been developed, including turnips, bok choi, pak choi, tat soi (which are sometimes referred to as Chinese cabbages, or Chinese white- or Chinese flat cabbages, or celery mustard), pak choi sum (Chinese flowering cabbage), and napa cabbage (also called celery cabbage or pe tsai), among others. The species is thought to have originated in Europe, with many varieties developed in Asia, but its numerous varieties are now widely cultivated commercially and in home gardens in temperate and north temperate regions throughout the world. Some varieties have become naturalized and are considered weeds in regions of China and North America.


 
B. rapa, formerly known as B. campestris, shows considerable variation in growth form and characteristics across the many cultivars, this species has, in general, a flat or globose root (in the case of turnips) without an elongated crown (as found in the rutabagas and kohlrabi, which are derived from B. olearacea), with stems that grow typically grow 30 to 120 cm (11.75 to 47.25 in), although in some cultivars up to 190 cm (75 in) tall. The leaves are large, soft, smooth or soft-hairy leaves, up to 50 cm (20 in) long, pinnatifid (deeply lobed) or lyrate (deeply lobed, but with an enlarged terminal lobe and smaller lateral lobes), which clasp the stem and may form a more or less dense head. The yellow, four-parted and cross-shaped flowers are small, usually less than 2 cm (0.75 in) long, and produce siliques—capsular fruit that dehisces (splits open) when mature—that may be up to 6 cm (2.5 in) long.

Photographic Location: Along the highway in Wilson County Tennessee.