Greek kentron — a spur, ather — a barb, referring to the pappus, which is of stiff, barbed bristles.
Annual or perennial herbs or subshrubs, glabrous to hairy. Stems prostrate to erect. Leaves along stems, alternate, margins toothed or lobed. Capitula diskoid, usually solitary, terminal on branches, with or without stalks. Involucral bracts in several rows, overlapping, unequal, inner ones membranous, outer leaf-like. Receptacle flat. Florets bisexual, tubular, purple or blue. Achenes cylindrical, 10-ribbed, glabrous. Pappus of deciduous, stiff, barbed bristles, sometimes absent.
Membranous inner and leafy outer involucral bracts.
3 species from C America and tropical S America; possibly 1 species native to Australia.
Source: (2002). Asteraceae. In: . Horticultural Flora of South-eastern Australia. Volume 4. Flowering plants. Dicotyledons. Part 3. The identification of garden and cultivated plants. University of New South Wales Press.