1. Cayaponia quinqueloba (Raf.) Shinners (melonleaf)

Arkezostis quinqueloba Raf.

Bryonia boykinii Torr. & A. Gray

C. boykinii (Torr. & A. Gray.) Cogn.

C. grandifolia (Torr. & A. Gray) Small

Melothria grandifolia Torr. & A. Gray

Map 1622, Pl. 372 a

Plants monoecious perennial vines with slender rhizomes. Stems to 4 m or more long, slender (1–2 mm in diameter), glabrous or sparsely (more densely on young growth) pubescent with short, nonsticky, spreading hairs, not strongly roughened, the tendrils usually unbranched. Leaves long-petiolate, the petiole 3–5 cm long, lacking glands at the tip, with sparse to moderate spreading hairs. Leaf blades 5–11 cm long, 6–13 cm wide, broadly ovate to nearly circular in outline, palmately moderately 5-lobed with 3 major lobes and 2 minor lobes, the lobes broadly triangular to triangular or ovate, with sharply pointed tips and broadly to narrowly rounded (mostly more than 90°) sinuses, cordate at the base, the margins otherwise sparsely toothed, the surfaces sparsely to moderately roughened with inconspicuous, short, nonsticky, pustular-based hairs. Flowers solitary or in small clusters in the leaf axils, the main stalk 3–5 mm long, the clustered flowers with individual stalks 1–2 mm long, those of the pistillate flowers elongating to 3 mm at fruiting. Calyx lobes 1–3 mm long. Corollas 4–6 mm wide, saucer-shaped to broadly bell-shaped, the usually 5 lobes 3–5 mm long, greenish white to white. Staminate flowers with the stamens distinct. Pistillate flowers with 3 staminodes, the ovary with 1 or 2 ovules per placenta, the stigma 3-lobed. Fruits solitary or paired, juicy berries, 1.2–1.8 cm long, thin-walled, indehiscent, ovoid or ellipsoid, with a stalk 2–3 mm long, the surface red (rarely yellow), smooth (not spiny), glabrous, glossy. Seeds 1–3, 6–9 mm long, 4–6 mm wide, more or less oblong in outline, somewhat flattened, pointed at the tip, with a pair of shallow, blunt lobes toward the base, black. June–August.

Uncommon in the Mississippi Lowlands Division (Florida to Texas north to Missouri). Swamps, bottomland forests, and banks of streams and rivers, usually climbing on shrubs and forming mats.

Two species of Cayaponia have been described in the southeastern United States. Cayaponia grandifolia was distinguished by having fruits 16–20 mm long and the largest leaf blades more than 10 cm wide, and C. quinqueloba (C. boykinii) was distinguished by having fruits 12–14 mm long and leaf blades less than 10 cm wide. Although there is considerable variation in leaf size and lobing, this is not correlated with fruit size or other characters. Thus, only one species is recognized here. The name C. quinqueloba has priority over C. boykinii and C. grandifolia (Shinners, 1957). However, critical examination of type collections of the names in question may lead to further reevaluation of the nomenclature and taxonomy of the complex in the future.