1. Hesperis matronalis L. (dame’s rocket)

Pl. 322 f, g; Map 1355

Plants biennial or perennial herbs, terrestrial. Stems 50–120 cm long, erect, branched from the base and usually also in the upper half, pubescent with 2-branched and unbranched hairs, sometimes also with very sparse glands. Leaves alternate and basal, (2–)4–20 cm long, the lower leaves petiolate, the upper ones often sessile, not clasping, the leaf blades lanceolate to ovate-lanceolate, the margins toothed, pubescent on the upper surface with unbranched hairs and on the undersurface mostly with 2-branched hairs. Inflorescences panicles, the lower branches subtended by reduced leaves. Sepals 5–8(–10) mm long, ascending, oblanceolate. Petals (11–)15–25 mm long, not lobed, pink to purple, rarely white. Styles 3–4 mm long. Stigma lobes decurrent. Fruits ascending, straight to slightly arched upward, (4–)6–10(–14) cm long, more than 10 times as long as wide, linear, circular in cross-section, not beaked except for the persistent style, each valve with a midnerve and sometimes 2 lateral, longitudinal nerves, dehiscing longitudinally. Seeds in 1 row in each locule, 2.1–3.0(–4.0) mm long, oblong-elliptic in outline, somewhat flattened, usually with narrow wings at both ends, the surface with a fine, netlike or honeycomb-like pattern of ridges and pits, sometimes roughened, reddish brown. 2n=12, 14, 16, 24, 26, 28, 32, but counts other than 2n=24 may be erroneous (Al-Shehbaz, 1988b). May–June.

Introduced, widely scattered in the state (native of Europe, introduced widely in North America, mostly east of the Rocky Mountains). Railroads, roadsides, and open, disturbed areas.

This attractive plant has a long history of cultivation for its fragrant, showy flowers. In recent years, dense colonies have become more common along roadsides in the state. Plants with the petals nearly white occasionally grow intermixed with pink- or purple-flowered plants.