78. Rothmannia Thunberg, Kongl. Vetensk. Acad. Handl. 37: 65. 1776.
野栀子属 ye zhi zi shu
Authors: Tao Chen & Charlotte M. Taylor
Shrubs or large trees, unarmed. Raphides absent. Leaves opposite and generally isophyllous or frequently apparently verticillate in whorls of 3 due to marked anisophylly grouping 2 leaves at a node plus an apparently single leaf on a short to reduced axillary branch, sometimes with domatia; stipules persistent, interpetiolar, triangular. Inflorescences terminal or pseudoaxillary, congested-cymose and several flowered or reduced to 1 flower, sessile or pedunculate, bracteate or bracts reduced. Flowers sessile to pedicellate or pedunculate, bisexual, monomorphic. Calyx limb velvety pubescent inside, truncate to 5-lobed. Corolla white to pale green with red or purple to brown spots, narrowly to broadly funnelform or campanulate, often fleshy to leathery, glabrous inside; lobes 5(-7), convolute in bud to left or right depending on species. Stamens 5(-7), inserted in corolla tube, included or partly exserted; filaments short or reduced; anthers dorsifixed. Ovary partially to perhaps completely [1 or]2-celled, ovules numerous on 2 to several large parietal or perhaps sometimes axile placentas; stigma clavate, with receptive surface confined to shortly bilobed apex, exserted or included. Fruit baccate, thickly fleshy to leathery, globose to ellipsoid and sometimes relatively large, smooth or ridged, yellow to brown, with calyx limb persistent; seeds numerous, large, angled to sublenticular, embedded in pulp.
At least 30 species: tropical Africa, Asia, and Madagascar; one species in China.
Rothmannia does not seem at all well known in Asia, as to species or generic limits. The distinctive growth form of Rothmannia, with some or several nodes bearing apparently unequal and ternate leaves, is due to the development of one very short axillary branchlet that bears one leaf (the other being reduced to absent). The flowers are often if not usually nocturnal. Rothmannia has been described by some authors as having a 1-locular ovary with parietal placentas, at least in Africa (Bridson & Verdcourt, Fl. Trop. E. Africa, Rub. (Pt. 2), 511-512. 1988), but the Asian species have 2-celled ovaries with apparently axile placentas (Puff et al., Rubiaceae of Thailand, 60. 2005).
The African species Rothmannia longiflora Salisbury is occasionally cultivated in tropical Asia, including Hong Kong (S. Y. Hu & K. H. Yung 403, MO!). This species has elliptic leaves that are 6-11 × 3-5 cm and relatively large showy flowers, with the tubular calyx limb 5-10 mm and subtruncate or with small lobes 1-4 mm, and a slenderly funnelform, relatively large corolla with tubes 12-14 cm and lobes 1-4 cm.