1. Apium graveolens L. (celery)

Pl. 203 c–e; Map 843

Plants perennial, with taproots, glabrous. Stems 30–100 cm long, erect or ascending, not thickened at the base. Leaves alternate and often also basal (a few basal leaves often present at flowering), short- to long-petiolate, the sheathing bases not or only slightly inflated. Leaf blades 4–18 cm long, oblong to broadly obovate in outline, 1 time pinnately compound with 3–9 leaflets, the leaflets 8–50 mm long, obovate or narrowly to broadly wedge-shaped, 1 or 2 times ternately lobed and/or toothed, the lobes mostly obovate or wedge-shaped, broadly to narrowly tapered at the base, mostly rounded at the tip. Inflorescences terminal and lateral, compound umbels, short-stalked to sessile or less commonly long-stalked. Involucre absent, but the subtending leaves sometimes appearing as an involucre in sessile inflorescences. Rays 7–15, 0.7–2.5 cm long. Involucel absent. Flowers 7–17 in each umbellet, the stalks 1–6 mm long. Sepals minute triangular teeth. Petals broadly ovate, rounded at the tip, white. Ovaries glabrous. Fruits 1.0–1.5 mm long, broadly oblong-elliptic to depressed-circular in outline, rounded at the base, flattened laterally, glabrous, brown, each mericarp narrowed along the commissures, with 5 ribs, these narrow, more or less rounded, lacking wings. 2n=22. June–August.

Introduced, known thus far only from St. Louis (native of Europe, Asia; introduced sporadically in the New World). Railroads.

Apium graveolens is sometimes divided into two or more subspecies. The edible celery, with thick juicy petioles, is var. dulce (Mill.) Pers. The var. graveolens contains weedy plants with slender petioles, which usually become spread as seed contaminants. The few specimens from Missouri appear to represent the latter phase.