5. Catharanthus G. Don, Gen. Hist. 4: 71, 95. 1837.
[I]
Periwinkle [Greek katharos, pure, and anthos, flower, alluding to neatness and beauty of flowers]
David E. Lemke
Subshrubs or herbs, perennial [annual]; latex milky. Stems erect, ascending, or decumbent, unarmed, glabrous or eglandular-pubescent. Leaves deciduous, opposite or occasionally subopposite, petiolate; stipular colleters interpetiolar and intrapetiolar; laminar colleters absent. Inflorescences axillary, solitary flowers or pairs of flowers, short-pedunculate or sessile. Flowers: calycine colleters absent; corolla white, pink, red, magenta, or red-violet, salverform, aestivation sinistrorse; corolline corona absent; androecium and gynoecium not united into a gynostegium; stamens inserted at top [middle] of corolla tube; anthers connivent, not adherent to stigma, connectives not appendiculate or enlarged, locules 4; pollen free, not massed into pollinia, translators absent; nectaries 2, elongate and often exceeding ovary. Fruits follicles, solitary or paired, erect, green, slender and weakly moniliform, terete or compressed, surface striate, pubescent. Seeds ovoid [oblong], flattened, not winged, not beaked, not comose, not arillate. x = 8.
Species 8 (1 in the flora): introduced; Asia (India), Indian Ocean Islands (Madagascar, Sri Lanka); introduced also nearly worldwide in tropical and subtropical regions.
At various times the generic names Vinca, Lochnera Reichenbach, and Catharanthus have been used for the species treated here, but W. T. Stearn (1966) argued convincingly that the latter name is the legitimate one for the genus. While Catharanthus and Vinca have been shown to be somewhat closely related (A. O. Simões et al. 2016), they have disjunct native geographic ranges (India, Madagascar, and Sri Lanka for Catharanthus, Europe and western Asia for Vinca) and are easily distinguished by the characteristics given in the generic key.
SELECTED REFERENCE van Bergen, M. and W. Snoeijer. 1996. Series of revisions of Apocynaceae XLII: Catharanthus G. Don. The Madagascar periwinkle and related species. Wageningen Agric. Univ. Pap. 96: 1–120.
