Description from Flora of China
Calcitrapa Vaillant; Centaurea sect. Hyalaea Candolle; Chartolepis Cassini; Cnicus Linnaeus, nom. cons.; Hyalea Jaubert & Spach; Jacea Miller.
Herbs, annual, biennial, or perennial. Leaves concolorous. Capitula heterogamous, 1 to numerous or paniculate-corymbose or paniculate-racemose. Involucre globose, ovoid, campanulate, or bowl-shaped. Phyllaries imbricate; apical appendage fimbriate, spiny, or scarious. Florets few to many; outer florets sterile, enlarged and radiant or ± as long as inner ones, without staminodes; inner florets bisexual. Corolla yellow, white, pink, or purple. Stigmatic branches short. Achene sparsely pubescent to glabrescent or glabrous, apical rim denticulate or smooth. Pappus usually present, of two types of elements; outer pappus elements bristlelike, usually in many rows, rarely in 1 row, persistent or caducous, scabrid; inner pappus elements short, usually scalelike.
All of the native species in China occur in Xinjiang. Centaurea nigrescens Willdenow, native to Europe, is grown as a garden plant at the Summer Palace in Beijing.
About 300-450 species: most in C and SW Asia and Mediterranean region; seven species (one introduced) in China.
(Authors: Shi Zhu (石铸 Shih Chu); Ludwig Martins)