Florida milkvine or spinypod

Vincetoxicum floridanum Vail, Bull. Torrey Bot. Club 26: 428. 1899; Odontostephana floridana (Vail) Alexander

Vines, herbaceous. Stems 1–5, twining, 100–500 cm, hir­sute with eglandular and incon­spicuous glandular trichomes. Leaves with 2 colleters on each side of petiole; petiole 1–6 cm, hirsute with eglandular and inconspicuous glandular trichomes; blade narrowly ovate, oblong, or elliptic (ovate or cordate), 3.5–11 × 2–12 cm, base shallowly to deeply cordate, with 2–6 laminar colleters, apex acute to acuminate, surfaces hirsute with eglandular and inconspicuous glandular trichomes. Inflorescences solitary, racemiform (umbelliform), extra-axillary, pedunculate, 3–10-flowered; peduncle 0.3–1(–5) cm, hirsute with eglandular and inconspicuous glandular trichomes. Pedicels 5–15 mm, hirsute with eglandular and inconspicuous glandular trichomes. Flowers: calyx lobes spreading, elliptic to ovate, 1–2.5 mm, apex acute to acuminate, hirsute with eglandular and inconspicuous glandular trichomes; corolla pale yellow to green abaxially (maroon or maroon tinged), maroon to brown to purple (green to yellow, sometimes maroon tinged), with a cream to yellow ring at base of corona adaxially, faintly reticulate, rotate-campanulate, tube 1–1.5 mm, lobes spreading, margins plane, lance­olate to oblong, 3–7 mm, minutely hirtellous abaxially, glabrous adaxially; corona united to column near base, of 5 united, fleshy segments, each with 2 small lateral lobes at apex, shorter than medial lobe, forming a lobed sheath that equals style apex, adaxial appendages incurved, incumbent on anthers, dark maroon, 1.5–2 mm, glabrous; apical anther appendages bright white with maroon patch at base, truncate; style apex yellow to yellow-green, maroon tinged in center, pentagonal, flat. Follicles not striate, lance-ovoid to ellipsoid, 7.5–11 × 1–2.5 cm, apex acuminate, sparsely to moderately muri­cate, sparsely and minutely hirsute. Seeds brown, ovate (orbicular), 7–8 × 5–6 mm, margins broadly winged, chalazal end entire, faces rugose; coma 1.5–2.2 cm.

Flowering Apr–Aug(–Oct); fruiting Jul–Oct(–Dec). Sandy and calcareous soils, sandhills, hillslopes, bluffs, sinks, ravines, hammocks, mixed-hardwood, oak-hickory, and pine forests, cypress domes, streamsides, swamps; of conservation concern; 0–70 m; Fla., Ga.

Matelea floridana is known primarily from northern peninsular Florida. Widely disjunct populations in Hendry and Miami-Dade counties are documented only by vegetative specimens that cannot be identified with any confidence; however, other than the highly dissimilar, decumbent M. pubiflora, no other Matelea occurs in peninsular Florida. A smaller disjunction is represented by an apparent gap in the distribution between Suwannee County and the Panhandle. Although widely distributed in the state, its occurrences in Florida are scattered, and M. floridana is considered state-endangered. The occurrence of M. floridana in Georgia is confirmed at a single location in Thomas County, but it has been reported from two other counties in the southwestern corner of the state. Specimens of M. floridana have been identified as M. carolinensis; however, that species is not known from Florida and differs by corona segments with the medial lobe shorter than the lateral lobes and more rounded corolla lobes (compared to the medial corona lobe much longer than the lateral lobes and acute to obtuse corolla lobes in M. floridana).