1. Chelidonium majus L. (celandine, greater celandine, tetterwort)

Pl. 475 a, b; Map 2173

Plants perennial herbs, with thick, sometimes branched rhizomes; sap yellow to yellowish orange. Aerial stems 30–80 cm long, sometimes branched, loosely to strongly ascending, sparsely pubescent with fine, more or less spreading, multicellular hairs. Leaves basal (several) and alternate (few to several) along the stems, 15–35 cm long, the basal leaves long-petiolate the stem leaves mostly short-petiolate to sessile. Leaf blades pinnately deeply lobed or compound into 3–7 lobes or leaflets, these oblong-obovate, rounded at the tip, the margins irregularly scalloped and/or bluntly toothed, usually also shallowly to deeply few-lobed, the upper surface green, glabrous, the undersurface pale and glaucous, glabrous or sparsely hairy. Inflorescences terminal and sometimes also axillary, umbellate, the umbels sessile or stalked, few-flowered, occasionally reduced to a solitary flower, the individual flower stalks 0.5–3.5 cm long, ascending, slightly expanded at the tip but not forming a cup or disc, each with a bract at the base, this 0.5–2.0 mm long, broadly oblong-ovate, glabrous. Sepals 2, free, shed individually as the flower opens, 8–12 mm long, broadly elliptic-ovate and deeply concave (cupped around the flower), broadly pointed at the tip. Petals 4, 8–14 mm long and wide, broadly obovate, rounded at the tip, yellow. Stamens 12 to numerous. Ovary tapered to a minute, persistent style 0.5–1.0 mm long, the stigma more or less capitate, with 2 shallow, ascending lobes (appearing notched). Fruits 2–5 cm long, erect or ascending, narrowly cylindric, glabrous, dehiscing longitudinally from the base by 2 valves. Seeds 1.2–1.8 mm long, ovoid, with a short, winglike aril along 1 side, the surface otherwise with a network of relatively coarse but shallow ridges and pits, reddish brown to brown, shiny. 2n=12. April–August.

Sepals 8–12 mm long, glabrous; petals 8–14 mm long; fruits narrowly cylindric, glabrous, dehiscent from the base

Introduced, uncommon, known thus far only from Franklin, Jackson, and St. Louis Counties (native of Europe, Asia; introduced widely in the northeastern and northwestern U.S.; Canada). Gardens and disturbed areas.

The brightly colored sap is a skin irritant and has been used medicinally to remove warts. The species is sometimes cultivated as an ornamental in gardens, but tends to spread aggressively by seeds at suitable sites.