21. Erysimum L. (wallflower)
Plants annual, biennial, or perennial herbs (shrubs elsewhere), terrestrial,
pubescent with sessile, 2- or more branched hairs, the hairs often positioned
flat along the stem or leaves and with 2 opposite branches, thus appearing as a
straight line. Stems erect or ascending, unbranched below the inflorescence or
several-branched. Leaves basal and alternate, sessile or short-petiolate, not
clasping, simple, the margins entire, wavy, toothed, or pinnately lobed.
Inflorescences racemes or panicles, the flowers not subtended by bracts. Sepals
linear to narrowly oblong, erect, green, hairy. Petals unlobed, light yellow to
yellow or orange (white, pink, or purple elsewhere). Styles variously absent or
to 5 mm long (to 12 mm elsewhere), the stigma more or less 2-lobed. Fruits
erect, ascending, or horizontally spreading, more than 10 times as long as wide,
linear in outline, circular or 4-angled in cross-section, dehiscent
longitudinally. Seeds in 1 row in each locule, the surface with a fine, netlike
or honeycomb-like pattern of ridges and pits, sometimes also finely roughened,
yellowish orange to reddish brown. About 150 species, North America, Europe, Asia, Africa.