Plant: Annual, 5-50 cm, taprooted; stem much-branched throughout, ribbed, hollow

Leaves: mostly cauline, opposite or alternate; petiole 2-4 cm; petiole base generally sheathing stem; blade 1-5 cm, round, finely ternately dissected, segments 5-25 mm, linear to oblong

INFLORESCENCE: umbels compound, peduncled or not, from axils or opposite upper leaves; bracts, bractlets 0; rays 2-3, pedicels few, both unequal, spreading

Flowers: many, small; calyx lobes 0; petals wide, white, tip acute, not incurved; ovary inferior, 2-chambered; projection atop ovary flat to barely conic; stamens 5; pistil 1, ovary inferior, 2-chambered

Fruit: 2 dry, 1-seeded halves that separate from each other but generally remain attached for some time to a central axis, 1-1.5 mm, elliptic-cordate, compressed side-to-side, papillate-roughened to becoming glabrous; ribs thread-like; oil tubes per rib-interval 1; fruit axis divided to base; Seed: face concave

Misc: Chaparral, coastal scrub, etc.; 0-1500 m.