1. Berteroa incana (L.) DC. (hoary alyssum)

Pl. 314 d, e; Map 1319

Plants annual (biennial or perennial elsewhere), terrestrial. Stems (20–)35–80(–110) cm long, erect, usually branched, densely pubescent with mostly stellate, appressed hairs mixed with unbranched ones. Leaves numerous, alternate, the basal leaves usually withering by flowering, sessile or the lowermost leaves short-petiolate, the bases not clasping, 1–5 cm long, the blades oblanceolate, entire, densely pubescent with mostly stellate, appressed hairs. Inflorescences panicles, the lower branches subtended by reduced leaves. Sepals 1–2 mm long, ascending, elliptic to lanceolate, stellate-pubescent, becoming detached soon after the flower opens. Petals (4.0–)5.0–6.5(–8.0) mm long, deeply 2-lobed at the tip, white. Styles 1–3(–4) mm long. Fruits erect, straight or arched, (4–)5–8(–10) mm long, 2–3 times as long as wide, elliptic, broadly elliptic in cross-section and somewhat flattened, stellate-pubescent, eventually dehiscing longitudinally, each valve with a faint midnerve near the base. Seeds in 2 rows in each locule, 1.5–2.3 mm long, circular to broadly obovate in outline, flattened, the margin narrowly winged, the surface with a fine, netlike or honeycomb-like pattern of ridges and pits, brown to dark brown. 2n=16. May–September.

Introduced, uncommon and widely scattered (native of Europe and Asia, widely naturalized in North America, mostly to the north and east of Missouri). Railroads, roadsides, and open, disturbed areas.