Rivea

Accepted name/Authority/Place of publication:

Rivea Choisy, Mém. Soc. Phys. Genève 6: 407. [Conv. Or. 25] (1834).

Tribe:

Ipomoeeae

Habit:

Shrubs or woody climbers; young parts shining silvery or white pubescent.

Leaves:

Leaves petiolate, ovate to cordate, with 2 prominent dark glands at base of midrib.

Inflorescences:

Inflorescences axillary, cymose, often bracteose.

Flowers:

Flowers showy, nocturnal, fragrant; sepals equal to markedly unequal, persistent, subwoody, and reflexed in fruit; corolla salverform, with a long cylindrical tube and a broad limb flaring at right angles; stamens included, filaments hairy at insertion, glabrous and free above, anthers linear-oblong; pollen spinulose; pistil included or stigmas exserted, ovary 4-celled, 4-ovuled, style filiform, stigmas 2, linear-oblong.

Pollen:

Pollen spinulose.

Fruits:

Fruit indehiscent, woody, brown, thick-walled, shattering irregularly, inner layer mealy-fibrous.

Seeds:

Seeds 4 or fewer, embedded in mealy pulp, glabrous.

Distribution:

Tropical Asia. map

Number of Species:

Infrageneric Characters:

Ooststroom (1943) brought Rivea back nearly to its original circumscription: shrubby plants with nocturnal, salverform flowers, 2 elongate (rather than biglobose) stigmas, and woody fruits that break up irregularly and contain a dry, mealy pulp in which the 1–4 seeds are embedded. As such, the genus is entirely Asian and all American species are removed to other genera.
Although molecular evidence suggests that Rivea be subsumed into Ipomoea the species have an immediately recognizable aspect and it is a matter of practicality to recognize them as distinct.

References:

Ooststroom, S.J. van. 1943. The Convolvulaceae of Malaysia, IV. The genera Mina, Lepistemon, Stictocardia, and Argyreia. Blumea 5(2): 339–411. Staples, G. 2007. Edinb. J. Bot. 64: 213–223. Staples, G. Flora of Thailand 10(3): 457-459.