General:
Perennial herb from fibrous or slightly tuberous roots; stems one to several, erect to ascending, branched in inflorescence, 15-60 cm tall, soft-hairy or smooth, somewhat hollow.

Leaves:
Basal and stem leaves lanceolate or narrowly egg-shaped, the blades 2-14 cm long, 0.7-3 cm wide, entire or slightly toothed, bases abruptly narrowed or rounded, tips pointed to blunt, the stalks stout, as long or longer than blades; stem leaves with shorter stalks, alternate; reduced to unstalked bracts above, sometimes opposite.

Flowers:
Inflorescence few- to several-flowered cymes; flower stalks lengthening in fruit, to 15 cm long; receptacle smooth; petals 5 (to 12), distinct, yellow, 5-14 mm long, 2-8 mm wide, nectary on upper surface, the nectary scale smooth, broadly egg-shaped; sepals 5, spreading or bent back from base, 2-6 mm long, 1-4 mm wide, somewhat hairy; stamens 25-90; pistils 10-60.

Fruits:
Achenes, 10 to 60 in an egg- to globe-shaped head 3-7 mm long, 4-8 mm wide, the achenes plump, 1.6-2.8 mm long, 1.2-2 mm wide, smooth or rarely stiff-hairy; beaks lanceolate to awl-shaped, straight or somewhat curved, 0.4-1.2 mm long.

If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.