Lax hornpod

Cynoctonum petiolatum J. F. Gmelin, Syst. Nat. 2: 443. 1791; C. mitreola (Linnaeus) Britton; C. succulentum R. W. Long

Herbs or subshrubs, 5–80(–100) cm. Leaves petiolate or subses­sile; blade ovate, narrowly ovate, or elliptic, 2–8 × 0.5–4.5 cm, larger leaves 2–3.5 times as long as wide, base cuneate, surfaces sparsely appressed-hairy or glabrous. Inflorescences lax, flowers mostly shorter than internodes, ultimate branches 2–15 cm. Flowers subsessile; calyx glabrous; corolla usually white, sometimes mauve, 1.5–2.5 mm, throat pilose. Capsules 2–3.5(–5) mm, horns smooth or lightly tuberculate on inner faces. Seeds ellipsoid or depressed-subglobose, 0.5–0.7 mm, reticulate. 2n = 20.

Flowering Jul–Aug. Marshes, swamp forests, ditches, along roads, grassy plains, fields, often moist, sandy, or rocky places, light shade; 0–1000 m; Ala., Ark., Fla., Ga., La., Miss., Mo., N.C., Okla., S.C., Tenn., Tex., Va.; Mexico; West Indies; Central America.

Recent work (K. M. Neubig et al., unpubl.) would indicate, based on DNA and morphological data, there are at least two additional species that should be segregated from Mitreola petiolata, including some Mexican and Central American material and all South American and Old World material included by Leeuwenberg (1974) in his broadly defined M. petiolata. Thus, the distribution of M. petiolata in the narrow sense is primarily North American, extending south to Guatemala and in the Caribbean.