Thlaspi bursa-pastoris Linn.
Annual or biennial, up to 45 cm tall, erect, glabrous or hairy with simple or branched hairs. Basal leaves rosulate, very variable, usually pinnatifid (lyrate to almost entire), 5-8-jugate, shortly stalked, usually up to 8 cm long, 2 cm broad; cauline leaves smaller, sessile. ± auricled and clasping the stem. Racemes many flowered, up to 30 cm long in fruit. Flowers c. 2.5 mm across, white; pedicels up to 18 mm long in fruit, spreading. Sepals c. 1.5 mm long, l mm broad. Petals c. 2.5 mm long, 1 mm broad, obovate-oblong, cuneate. Stamens c. 1.5: 2 mm long. Siliculae obcordate- triangular, 5-9 mm long, 4-6 mm broad; valves usually with straight margins; apical notch wide, V-shaped ; style c. 0.5 mm long, hardly or not exceeding the notch; septum c. 1 mm broad, seeds 6-12 in each locule, c. 1 mm long, oblong-elliptic, pale brown.
Fl. Per.: March June.
Type: Described from Europe, Herb. Linn. no. 825/15 (LINN).
Distribution: Cosmopolitan in cooler climates mostly.
‘Shepherds purse’ is a very variable species, especially in size and shape of leaves, siliculae and hairiness. It has strong tendency for developing distinctive populations because of self pollination. Some of its forms superficially resemble C. rubella Reuter, from the Mediterranean region, with somewhat concave margin of the siliculae, but the sepals are not pinkish and petals not so small.
Seeds contain about 15-20% oil.