17. Ranunculus repens L. (creeping buttercup)

R. repens var. pleniflorus Fernald

Pl. 518 g; Map 2383

Plants perennials. Roots not tuberous. Stems 10–60 cm long, prostrate and mat-forming, occasionally some of the stems loosely ascending from a spreading base, rooting at the nodes, sparsely to densely pubescent with loosely appressed to spreading hairs, without bulbils, the base not bulbous. Basal leaves present at flowering, long-petiolate, the blade 1.0–8.5 cm long, 1.5–10.0 cm wide, ovate to kidney-shaped, usually compound, with 3 primary leaflets, the central leaflet usually stalked, the base mostly deeply cordate, the leaflets obovate to bluntly rhombic, 1 or 2 times again 3-lobed or -parted, the ultimate segments obovate to elliptic or occasionally narrowly oblong, bluntly to sharply pointed at the tip, the margins otherwise irregularly toothed. Stem leaves similar to basal leaves but with shorter petioles and somewhat less divided blades having narrower segments. Sepals 5, 4–7 mm long, spreading or reflexed from the base (lacking a transverse fold), more or less plane. Petals 5 (more in doubled forms), 6–18 mm long, 5–12 mm wide, obovate to broadly obovate, longer than the sepals, yellow. Style present. Head of achenes 5–10 mm long at maturity, ovoid to more or less globose, the receptacle hairy or rarely glabrous. Achenes 2.6–3.2 mm long, flattened, the dorsal margin bluntly angled or narrowly ribbed, unwinged, the wall thick, smooth, glabrous, the beak 0.8–1.4 mm long, flattened, triangular to narrowly triangular, usually curved. 2n=14, 32. May–September.

Introduced, uncommon, sporadic, known only from historical specimens (native of Europe, Asia, introduced widely in North America south to South America, also Australia, Pacific Islands; in the U.S., widespread [including Alaska] except in the Great Plains region). Mesic upland forests; also moist, disturbed areas.

This species is grown as an ornamental and groundcover in gardens. A horticultural form with doubled corollas has been called var. pleniflorus and was collected once as an escape in Clay County (Steyermark, 1963).