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89. Tarenna Gaertner, Fruct. Sem. Pl. 1: 139. 1788.

乌口树属 wu kou shu shu

Authors: Tao Chen & Charlotte M. Taylor

Chomelia Linnaeus (1758), not Jacquin (1760, nom. cons.); Cupi Adanson; Webera Schreber.

Shrubs or trees, unarmed, often drying blackened. Raphides absent. Leaves opposite, sometimes with domatia; stipules persistent or occasionally tardily deciduous, interpetiolar or united around stem, triangular, often aristate. Inflorescences terminal, sometimes displaced to pseudoaxillary by subsequent growth, cymose to corymbiform, few to many flowered, sessile or pedunculate, bracteate or bracts reduced. Flowers pedicellate or sessile, bisexual, monomorphic, often fragrant. Calyx limb 5-lobed. Corolla white, pale green, or yellow, funnelform or salverform, inside glabrous or pubescent in throat; lobes 5, convolute in bud, usually strongly reflexed at anthesis. Stamens 5, inserted in corolla throat, exserted; filaments short or reduced; anthers dorsifixed. Ovary 2-celled, ovules 1 to numerous in each cell on axile placentas; stigma fusiform or linear, sulcate or striate, shortly 2-lobed at apex, exserted. Fruit baccate, leathery or thinly fleshy, globose to ellipsoid, black or perhaps sometimes white, with calyx limb deciduous; seeds several, medium-sized, plano-convex or concavo-concave, testa membranous, leathery, or crustaceous; endosperm fleshy or corneous; embryo small; cotyledon small, leaflike.

About 370 species: tropical and subtropical Africa, Asia, Madagascar, and Pacific islands; 18 species (12 endemic) in China.

The name Chomelia Linnaeus (1758) was applied to these plants for many years; however, the later homonym Chomelia Jacquin (1760), which applies to a wholly neotropical genus, is now conserved against the Linnaean name, so the Old World plants formerly known under Chomelia are now correctly known under Tarenna.

Most of the characters that distinguish species of Tarenna are found in the corollas and calyx limb, thus specimens of Tarenna are often difficult to identify when they only have fruit from which the calyx limb has fallen. The genus was not well known in China until the work of W. C. Chen (Acta Phytotax. Sin. 22: 139-174. 1984). Tarenna apparently has secondary pollen presentation. W. C. Chen (in FRPS 71(1): 370. 1999) described the stipules as caducous, but the specimens seen all have persistent or tardily deciduous stipules. The key here closely follows that of W. C. Chen in FRPS (loc. cit. 1999: 370-372), with its emphasis on pubescence characters and number of ovules per locule, for reference. Chen (loc. cit. 1999: 370-384) considered the form (i.e., raised vs. flat vs. impressed) of the leaf midrib adaxially to be consistent within a species, but specimens studied show variation within species and overlapping among most species.

1 Flowers with pedicels 18-30 mm.   14 T. sinica
+ Flowers subsessile or with pedicels to 13 mm   (2)
2 (1) Calyx lobes subulate, 3-5 mm.   7 T. lanceolata
+ Calyx lobes triangular to narrowly triangular, 2 mm or shorter   (3)
3 (2) Ovary with ovules 1 per cell; fruit with seeds 1 or 2.   2 T. attenuata
+ Ovary with ovules 2 to many per cell; fruit with seeds 1 to many   (4)
4 (3) Corolla tube longer than corolla lobes   (5)
+ Corolla tube as long as or shorter than corolla lobes   (9)
5 (4) Corolla villosulous to pilosulous outside; leaf blade densely villosulous to pilosulous.   17 T. yunnanensis
+ Corolla glabrous outside; leaf blade glabrous or sparsely puberulent, strigillose, or hirtellous abaxially   (6)
6 (5) Calyx lobes triangular-lanceolate, ca. 1.5 mm, strigillose; leaf blade abaxially glabrous or sparsely pilosulous or strigillose.   1 T. acutisepala
+ Calyx lobes triangular to broadly triangular, 0.5-1.5 mm, glabrous; leaf blade abaxially glabrous or sparsely puberulent or strigillose   (7)
7 (6) Leaves with secondary veins 12-14 pairs.   5 T. foonchewii
+ Leaves with secondary veins 6-9 pairs   (8)
8 (7) Ovary with ovules 6-9 per cell; calyx with hypanthium portion sparsely puberulent to hispidulous, lobes 0.8-1.5 mm; leaf blade drying papery or membranous, with secondary veins 6 or 7 pairs.   3 T. austrosinensis
+ Ovary with ovules ca. 17 per cell; calyx with hypanthium portion glabrous, lobes 0.5-0.8 mm; leaf blade drying leathery, with secondary veins 7-9 pairs.   12 T. polysperma
9 (4) Leaf blade glabrous on both surfaces   (10)
+ Leaves abaxially strigillose, hirtellous, hispidulous, pilosulous, or villosulous   (14)
10 (9) Branches becoming yellowish white or grayish white with age, sometimes resinous at apex; stipules deciduous usually through fragmentation.   4 T. depauperata
+ Branches green to brown or ashy gray, not evidently resinous at apex; stipules persistent or deciduous through fragmentation   (11)
11 (10) Leaf secondary veins 3-10 pairs; petioles 0.8-2 cm; inflorescences 4-9 × 4-9 cm; leaf blade 4.5-15 × 1.5-6 cm   (12)
+ Leaf secondary veins 7-13 pairs; petioles 1-3.5 cm; inflorescences 4-15 × 6-20 cm; leaf blade 13-25 × 5-12 cm   (13)
12 (11) Corolla tube 2-2.5 mm.   2 T. attenuata
+ Corolla tube 5-7 mm.   8 T. lancilimba
13 (11) Leaf secondary veins 8-13 pairs; calyx mealy puberulent; inflorescences subglabrous or puberulent, ca. 15 × 20 cm; ovary with 4 ovules per cell.   9 T. laticorymbosa
+ Leaf secondary veins 7 or 8 pairs [or 6 in Japan]; calyx glabrous; inflorescences glabrous, 4-10 × 6-15 cm; ovary with 2 ovules per cell.   18 T. zeylanica
14 (9) Leaves pubescent adaxially, at least on midrib   (15)
+ Leaves glabrous or glabrescent adaxially   (17)
15 (14) Corolla glabrous outside; fruit with seeds 1-6.   13 T. pubinervis
+ Corolla strigillose or hirtellous outside; fruit with seeds ca. 30   (16)
16 (15) Corolla tube 5-7 mm, lobes 11-12 mm, much longer than tube; leaf secondary veins widely spaced, 6-8 pairs.   10 T. laui
+ Corolla tube 3-4 mm, lobes 4-5 mm, slightly longer than or nearly as long as tube; leaf secondary veins well spaced to closely set, 5-12 pairs.   11 T. mollissima
17 (14) Corolla tube pubescent outside; leaf blade lanceolate or lanceolate-oblong, 12-29 × 4.5-10.5 cm, abaxially pubescent along principal veins.   16 T. wangii
+ Corolla tube glabrous outside; leaf blade narrowly elliptic, obovate, lanceolate, or oblong-obovate, 6-16 × 1.5-7 cm, abaxially subglabrous to scabrous, puberulent, or strigillose on blade and veins   (18)
18 (17) Ovary with ovules 5 or 6 per cell; pedicels rather slender, 5-10 mm; fruit ellipsoid; leaf blade abaxially sparsely strigillose.   6 T. gracilipes
+ Ovary with ovules 2 per cell; pedicels rather thick, 4-7 mm; fruit subglobose; leaf blade scattered subpapillose-pubescent, scabrous, or subglabrous.   15 T. tsangii

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