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.