| Resumo: |
Annual or perennial herbs, rarely shrubs, with hollow stems. Leaves alternate or rarely opposite, simple or variously compound; petioles usually sheathing at the base. Stipules minute or wanting. Inflorescence consisting of many-flowered, simple or compound umbels, heads or spikes; umbels and umbellules often involucrate. Flowers hermaphrodite or polygamous, actinomorphic or subzygomorphic, epigynous. Calyx of small teeth around the upper edge of the ovary or wanting. Petals 5, the apex often inflexed, valvate, sometimes wanting. Stamens 5; filaments inserted below the stylopodium (disk); anthers versatile. Ovary inferior, 2-locular, crowned by a conspicuous stylopodium; styles 2, free; stigmas small. Ovules solitary in each locule, pendulous, anatropous. Stylopodium 2-parted, subglandular. Fruit a schizocarp, crowned by the persistent stylopodium and the calyx, marked by longitudinal ribs between which oil-glands or tubes (vittae) in the grooves, and separating mostly from a filiform carpophore into 2 mericarps; the latter 1-seeded, indehiscent. Seed adnate to the pericarp. Endosperm abundant. Embryo minute. Nearly 3000 species in 270 genera in the temperate and subtropical regions chiefly in the northern hemisphere; only a few species in the tropics.
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