Caulophyllum

Michaux
Fl. Bor.-Amer. 1: 204. 1803.
Common names: Blue cohosh caulophylle
Etymology: Greek caulos, stem, and phyllos, leaf
Treatment appears in FNA Volume 3.

Herbs, perennial, deciduous, to 2-9 dm, glabrous. Rhizomes nodose, producing 2 leaves per year. Aerial stems present. Leaves caducous, cauline, 2-ranked, 1st leaf larger than 2d leaf, 2-4-ternately compound; petioles short or absent. Leaf blade broadly obovate in overall outline; rachis pulvinate; leaflet blades broadly obovate, entire or lobed, margins not toothed; venation pinnate to palmate. Inflorescences terminal, compound cymes. Flowers 3-merous, 6-20 mm; bracteoles caducous, 3-4, sepaloid; sepals 6, yellow, purple, red, brown, or green, petaloid; petals 6, fan-shaped, bearing nectar; stamens 6; anthers dehiscing by 2 apically hinged flaps; pollen exine reticulate; ovary bladderlike; placentation appearing basal; styles eccentric. Fruits not developed, ovary wall soon rupturing. Seeds 2, elevated on elongating stalk, naked at maturity; seed coat blue, fleshy, glaucous; aril absent. x = 8.

Distribution

North America, Asia.

Discussion

Species 3 (2 in the flora).

Caulophyllum species are understory herbs of mesophytic forests, alluvial flats, rich mesic slopes, and limestone slopes. The seeds of Caulophyllum are buoyant and showy and may be dispersed by water as well as other means; seed germination is hypogeal, the cotyledons remaining underground. Caulophyllum is occasionally cultivated in woodland gardens.

Key

1 Pistil 3–5 mm; style 1–2 mm; stamen filaments 1.5–2.5 mm; sepals 6–9 mm; inflorescences with 4–18 flowers; 1st leaf (2–)3-ternate; leaflets 5–10 cm. Caulophyllum giganteum
1 Pistil 1–3 mm; style 0.25–1 mm; stamen filaments 0.5–1.5 mm; sepals 3–6 mm; inflorescences with 5– 70 flowers; 1st leaf 3(–4)-ternate; leaflets 3–8 cm. Caulophyllum thalictroides