Operculina riedeliana (Oliv.) Ooststr.
Ooststroom, S.J. van (1939) Blumea 3: 366.
Twigs and petioles produce a milky exudate. Leaf blades about 5.5-14 x 4.5-13 cm, petioles about 1.5-5.5 cm long. Marginal teeth small and inconspicuous. Leaf blade margins undulate. Lateral veins about 10 on each side of the midrib. Juvenile or intermediate leaves much longer than wide, about 12.5-17 x 4-4.5 cm. Domatia are inconspicuous foveoles. Twigs quite pithy, pith white.
Flowers borne on thick pedicels about 2.5-3 cm long. Sepals dirty green brown in colour, +/- orbicular, about 13-017 mm long. Corolla about 4-5 cm long, broadly funnel-shaped. Anthers brown, about 6 mm long, staminal filaments about 12-13 mm long. Pollen white, surface smooth. Fide Ooststroom (1953). Ovary seated on a white disk. Ovary abut 2 mm long. Style + stigma about 18 mm long. Stigma +/- 2-lobed, each lobe about 1 mm diam. Ovules 5-6 per locule.
Fruits depressed globular, about 12-15 x 18-22 mm, very thin walled at maturity. Pedicels about 25 mm long, rather thick towards the apex. Sepals 5, orbicular, about 20 x 25 mm, persistent at the base of the fruit. Seeds up to four per fruit, each seed about 6-7 x 4.5-7 mm with two bands of short papillose hairs running around each seed. Each seed appears to have a two-layered testa, the outer testa thin, hairy and membranous, while the inner testa is exceedingly hard and horny. Cotyledons folded many times in a complex fashion. Endosperm intrusions visible between the folds in the cotyledons. Radicle about 6 mm long, slightly curved.
Cotyledons about 25-33 x 25-30 mm, deeply bilobed or notched at the apex, base auriculate, +/- 6-veined, the midrib divided into two veins near the base and not extending as a single entity towards the apex. Oil dots visible to the naked eye. First leaves glabrous, cordate to triangular, apex acuminate, base cordate to auriculate. At the tenth leaf stage: stem twining, leaf blade glabrous, cordate to linear-lanceolate, apex acute to almost subulate or acuminate, base cordate to obtuse. Margin undulate to shallowly crenate. Midrib depressed on the upper surface. 'Oil dots' very small, barely visible with a lens. Seed germination time 11 to 239 days.