Herbs, perennial, rarely biennial. Root fusiform or cylindrical, thickened, rarely fibrous. Stem erect, terete and often ribbed or striate, branching. Basal and lower leaves petiolate; petiole sheaths usually conspicuously broad; blade ternately or pinnately compound, hairy or glabrous. Umbels loose compound, terminal and lateral, terminal umbel with bisexual flowers, the lateral often with only staminate flowers; bracts few or absent, often caducous; rays numerous, spreading-ascending; bracteoles several, linear or lanceolate, entire; umbellules many-flowered. Calyx teeth triangular, lanceolate or obsolete. Petals white, rarely pinkish or pale yellow, obovate or obcordate, base cuneate, apex notched with a narrowly incurved lobule; outer flowers of the umbel often radiant with outer petals enlarged, broadly obovate, apex deeply 2-lobed. Stylopodium conic; styles short, erect or reflexed. Fruit obovoid, ovoid, broadly ovoid or suborbicular, strongly dorsally compressed, hairy or glabrous; dorsal and intermediate ribs filiform, sometimes raised, lateral ribs usually winged; vittae 1(–2) in each furrow, 2(–6) or absent on commissure, narrow, reaching to base of mericarp or clavate and much shorter than mericarp. Seed face plane, rarely slightly concave. Carpophore parted to base, usually persistent.
"Fr elliptic to obovate, strongly flattened dorsally, usually pubescent, the lateral ribs broadly winged, the others filiform; oil-tubes 2–4 on the commissure, solitary in the intervals, extending only part-way from the stylopodium toward the base of the fr, readily visible; carpophore bifid to the base; umbels large and compound, with numerous unequal rays; bracts lanceolate, deciduous; umbellets many-fld; bractlets linear; sep minute or none; pet white; outer fls of at least the marginal umbellets irregular, the outer pet enlarged and often bifid; tall, stout biennials and perennials with large, ternate or once pinnate lvs and broad, toothed or cleft lfls, the petioles sheathing and usually conspicuously expanded. 60, circumboreal, only one native to N. Amer."
Fruit very strongly dorsally compressed with thickened marginal wings and 3 filiform but often quite prominent dorsal ribs, glabrous to hairy; stylopodia conical, from a broad crenate-margined discoid base; vittae solitary in the valleculae, 0–2 on the commissure, slender to clavate, usually reaching most of the way down each mericarp but sometimes short; carpophore deeply bifid
Endosperm very flattened, shallowly rounded dorsally or sulcate at the vittae, flat or slightly concave centrally on the commissural face.
Perennial or biennial herbs, dwarf to gigantic, glabrous or more frequently ± densely furnished with unicellular, simple and subglandular hairs
Petals white to creamy, greenish or pink, the outer petals of the outer partial umbels slightly to very conspicuously radiate, the inner with an inflexed tip
Leaves simple and lobed to 1–2-pinnately or ternately divided with usually broad, dentate-incised to pinnatifid segments; sheaths often large, soft
Umbels numerous, compound, pedunculate; involucre present or absent; involucel usually of numerous narrow bracteoles
Calyx-teeth present, small and usually deciduous
Umbels compound; bracts 0; bracteoles several.
Calyx teeth minute or obsolete, unequal.
Perennial, biennial or annual herbs.
Marginal ridges expanded to form a broad wing, the dorsal ones filiform; wings somewhat thickened and closely appressed to those of the opposing mericarp.
Vittae solitary in the intervals, clearly visible from the exterior, and tending to be club-shaped, narrowing towards the base, with 2 in the commissural face.
Petals white (sometimes flushed with pink, especially in bud), often markedly unequal and radiate, those on the outer margin of the umbel being much larger than those on the inside, the whole umbel therefore tending to function like a capitulum in attracting insects, although the individual flowers remain quite distinct.
Fruit orbicular to broadly obovate, very strongly dorsally compressed, with a broad commissure.