2. Alyssum L. (alyssum)
Plants annual (perennial elsewhere), terrestrial, with stellate, mostly
appressed, nonglandular hairs. Stems 5–25 cm long, erect to spreading,
usually branched near the base. Leaves alternate, 6–15(–30) mm
long, the bases not clasping the stem, the margins entire. Inflorescences
racemes, without bracts. Sepals erect or ascending, 1.5–2.0 mm long,
oblong-elliptic. Petals shallowly notched at the tip, pale yellow or
cream-colored. Styles 0.3–0.7 mm long (longer elsewhere). Fruits
spreading or ascending, 3–5 mm long, about as wide as long or less than
2 times as long as wide, broadly oval to circular in outline, strongly
flattened parallel to the septum, usually shallowly notched at the tip,
sometimes with a minute style, dehiscing longitudinally, the valves lacking midnerves.
Seeds 1 or 2 per locule, 1.0–1.5 mm long, obovate to broadly elliptic
in outline, somewhat flattened, the margins narrowly winged, the surface
minutely roughened, orange. About 170 species, Europe, Asia, Africa, Alaska, Canada.
Some species of Alyssum are cultivated as garden ornamentals.