Stems usually solitary, mostly 1-2 cm across by 1-2 cm tall, hemispherical but appearing conical due to spination; tubercles solitary with groove on upper side; spines 30-75 per areole, slender and bristle-like, spreading, to 10(22) mm long; flowers ...
Stems solitary, few in a clump, or commonly branched to form small dense clusters of 20 or more stems, the individual stems mostly 2-4 cm thick, to 15 cm tall; tubercles on mature stems with upper surface grooved; spines about 20-60 per areole, sprea...
Annual or biennial; stems 1-4 from an herbaceous base, loosely corymbosely branched, mostly suffused with reddish-purple, 2-7 dm tall; leaves rather thin, dull green, denticulate to coarsely dentate, ovoid-oblong to lanceolate, usually subamplexicaul...
Rhizomatous, perennial herb, the rhizomes slender and unbranched; stems several, unbranched, clustered, somewhat woody at the base, 10-20 cm tall; leaves opposite, 8-15 mm long, 2.5-5.0 mm wide, sessile, oblong-lanceolate, tip rounded to acute, margi...
Stems pinkish-red, pinkish-yellow, or pinkish white; flowers with sepals pale creamy yellow or dull pale pinkish-purple with pinkish-red, pinkish-brown or pinkish-purple veins, connivent or spreading apically; dorsal sepal lanceolate to oblong, 15-18...
Perennial herb; stems one or a few from a branching base, 2-5 dm tall, glabrous or sparsely pubescent in the inflorescence; leaves once or twice parted into narrowly linear lobes; inflorescence corymbose (flat-topped); involucre of flower heads 8-10 ...
Perennial herb from a woody base; stems many, to 30 cm long; leaves many, mostly deeply and narrowly three-lobed, somewhat cruciform; flower heads terminal, solitary or in small clusters, somewhat bell-shaped; involucral bracts lance-shaped, about 4-...
Perennial herb from a woody base; stems single to many, 15-40 cm tall; leaves usually alternate, 1.7-3.8 cm long, 1.0-2.5 cm wide, mostly deeply and narrowly three-lobed, somewhat cruciform; flower heads terminal, solitary or in small clusters, somew...
Subrhizomatous perennial; stems 1-4 dm tall; leaves mostly basal, oblanceolate to obovate, dentate towards apex, lightly tomentose or glabrate at maturity; stem leaves few and much reduced upwards; heads radiate, erect, several to many in a corymbose...
Perennial from a slender, creeping, woody rhizome; stems few, usually erect, up to 4 dm high, puberulent throughout, glandular above; leaves entire, the lower ovate, the upper lanceolate, thin, minutely puberulent, amplexical, the upper sessile, the ...