erect herbs, caulescent, with taproots. Leaves alternate, petiolate, sheathing,
blade 2-3 times pinnately-decompound, ultimate segments small and narrow,
linear, leaves reduced upwards becoming sessile, wholly sheathing.
Inflorescence terminal and axillary, loosely compound umbel. Bracts numerous,
pinnate, usually reflexed, rays numerous, spreading or incurved after anthesis,
tightly compact in fruits, bracteoles numerous, toothed or entire, umbellules
many-flowered, central flowers usually sterile with enlarged purple petals.
Calyx teeth obsolete to conspicuous. Petals obcordate, with an inflexed apex,
white or yellow. Stylopodium conic, styles short. Fruits ellipsoid, dorsally
compressed, primary ribs bristly, secondary ribs winged with glochidiate
prickles. Seed face shallowly concave to nearly plane.