APIACEAE

CARROT FAMILY

Lincoln Constance

Annual, biennial, perennial herb (rarely shrub, tree), often from taproot
Stem often ± scapose, generally ribbed, hollow
Leaves basal and generally some cauline, generally alternate; stipules generally 0; petiole base generally sheathing stem; blade generally much dissected, sometimes compound
Inflorescence: umbel or head, simple or compound, generally peduncled; bracts present (in involucres) or not; bractlets generally present (in involucels)
Flowers many, small, generally bisexual (or some staminate), generally radial (or outer bilateral); calyx 0 or lobes 5, small, atop ovary; petals 5, free, generally ovate or spoon-shaped, generally incurved at tips, generally ± ephemeral; stamens 5; pistil 1, ovary inferior, 2-chambered, generally with a ± conic, persistent projection or platform on top subtending 2 free styles
Fruit: 2 dry, 1-seeded halves that separate from each other but generally remain attached for some time to a central axis; ribs on each half 5, 2 marginal and 3 on back; oil tubes 1–several per interval between ribs
Genera in family: 300 genera, 3,000 species: ± worldwide, especially temp; many cultivated for food or spice (e.g., Carum, caraway; Daucus; Petroselinum); some highly toxic (e.g., Conium). Underground structures here called roots, but true nature remains problematic. Mature fruit generally critical in identification; shapes generally given in outline, followed by shape in X -section of 2 fruit halves together.

HYDROCOTYLE

Perennial, creeping or sprawling, glabrous or hairy; rhizomes or stem rooting at nodes
Leaves simple; petiole scarious-stipuled, not sheathing; blade ± round, peltate or not, entire to deeply lobed
Inflorescence: umbels simple, open or dense; bracts 0 or inconspicuous; pedicels 0–many, spreading
Flower: calyx lobes 0 or minute; petals obtuse or acute, greenish or yellowish white to purplish, tip not incurved
Fruit elliptic to round, very compressed side-to-side; ribs subequal, thread-like, distinct or not; oil tubes 0 (but individual oil cells in fruit wall); fruit central axis not an obvious structure
Seed: face flat to convex
Species in genus: ± 100 species: worldwide, especially s hemisphere
Etymology: (Greek: water cup, apparently from leaf shape)

Native

H. verticillata Thunb.

Plant low, glabrous
Stem creeping
Leaf: petiole 0.5–25 cm, slender; blade 1–4 cm wide, round-peltate, crenate or very shallowly, crenately, subequally 8–13-lobed
Inflorescence: umbels small, 1–15-flowered, in a simple or forked spike; peduncles 1.5–20 cm; pedicels 0 or short
Fruit 1–3 mm, elliptic; ribs acute, evident
Ecology: Swampy ground, lake margins
Elevation: < 100 m.
Bioregional distribution: California Floristic Province, White and Inyo Mountains
Distribution outside California: to e N.America, S.America, Hawaii, s Africa
Flowering time: Apr–Sep
Synonyms: var. triradiata (A. Rich.) Fernald
Horticultural information: WET: 5, 7, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24; INV.