Pterolobium R. Br. ex Wight & Arn., Prodr: 283. 1834

Gagnon, Edeline, Bruneau, Anne, Hughes, Colin E., de Queiroz, Luciano Paganucci & Lewis, Gwilym P., 2016, A new generic system for the pantropical Caesalpinia group (Leguminosae), PhytoKeys 71, pp. 1-160 : 48

14. Pterolobium R. Br. ex Wight & Arn., Prodr: 283. 1834 Figs 23 , 24A-C

Cantuffa J.F. Gmel. (1791).

Reichardia Roth (1821), nom. illeg., non Roth (1787), nec Roth (1800).

Type.

Pterolobium lacerans R. Br. ex Wight & Arn., nom. illeg. ( Cantuffa exosa J.F. Gmel. = Pterolobium exosum (J.F. Gmel.) E.G. Baker; this now considered a synonym of Pterolobium stellatum (Forssk.) Brenan).

Description.

Lianas or scrambling / trailing shrubs, armed with prickles on shoots, as well as in pairs at the base of leaves. Stipules small, inconspicuous, subulate or triangular-subulate, caducous. Leaves alternate, bipinnate, ending in a pair of pinnae, 6-30 cm long; petiole and rachis pubescent to sparsely pubescent or glabrous; pinnae opposite, in 5-20 pairs; leaflets opposite, in 6-25 pairs per pinna, linear-oblong to elliptic-oblong, apex rounded to emarginate, sometimes mucronate, eglandular or punctate-glandular, 6-15 × 1.5-10 mm. Inflorescences terminal or axillary racemes, often aggregated into panicles, pubescent to glabrous, 4-25 cm long; bracts small, caducous. Flowers bisexual, sub-actinomorphic to zygormophic; calyx comprising a short hypanthium and 5 sepals, glabrous to pubescent, the lower sepal cucullate, covering the other 4 sepals in bud; petals 5, free, yellow to white, equal to slightly differentiated, claws pubescent, the median petal sometimes inrolled; stamens 10, free, filaments pubescent (occasionally glabrous); ovary pubescent, stigma chambered. Fruit a red to brown samara, the basal seed-containing portion 12-20 × 8-15 mm, reticulate or smooth, glabrous to pubescent, the upper suture much prolonged and broadly winged, the wing 20-45 mm long and usually wider distally, 1 (-2)-seeded.

Geographic distribution.

A genus of 10 species; one in southern tropical Africa, East Africa and Arabia, nine in SE Asia (one endemic to India, two in China, four in Indo-China [one endemic to Thailand, two extending to Malesia], three restricted to the Malay Peninsula and Archipelago [one endemic to the Philippines]).

Habitat.

Seasonally dry tropical upland evergreen forest, riverine and humid forest, woodland and wooded grassland.

Etymology.

From ptero - (Greek: wing) and lobion (Greek: pod, fruit), in reference to the fruit which is a samara.

Notes.

Vidal and Hul Thol (1974) published a revision of Pterolobium , with a key to species. We provide below a list of species currently accepted in the genus, taking into account the treatment of Pterolobium sinense as a synonym of Pterolobium macropterum ( Chen et al. 2010b).

References.

Roti-Michelozzi (1957); Brenan (1967: 40-42); Vidal and Hul Thol (1974, 1976); Hul Thol and Hideux (1977); Hou et al. (1996: 654-700); Chen et al. (2010b).

Figures

Figure 23. Pterolobium stellatum (Forssk.) Brenan. A part of flowering branch B flower C longitudinal section of flower D petal E stamen F infructescence with mature fruits G samara with part cut away to reveal seed. A-E from Richards 11275 F from Eggeling 3400 G from Sandwith 25. Drawn by L. M. Ripley, originally published in Flora of Tropical East Africa, Leguminosae subfamily Caesalpinioideae, page 41, fig. 7 (1967).

Figure 24. Pterolobium stellatum (Forssk.) Brenan. A inflorescences (P. van Wyk, Africa, unvouchered) B fruits (J. Anton-Smith, Africa, unvouchered) C close up of fruits (B. T. Wursten, Flora of Zimbabwe (http: // www. zimbabweflora. co. zw / speciesdata / image-display. php? species _ id = 127190 & image _ id = 1), Zimbabwe, unvouchered). Mezoneuron hildebrandtii Vatke D inflorescences (D. Du Puy, Majunga, Madagascar, Du Puy M 286 (P )) E fruits (D. Du Puy, Antsiranana, Madagascar, Du Puy M 273 (P )). Mezoneuron kauaiense (H. Mann) Hillebr. F flower and buds I fruit (D. Eickhoff, Wikicommons (https: // commons. wikimedia. org / wiki / Category: Mezonevron _ kavaiense) cultivated, Hawaii, U. S. A., unvouchered). Caesalpinia crista L. emend. Dandy & Exell (? Ticanto) G flowers H young fruits (P. Grard: Institut Francais de Pondichery, Andhra Pradesh, India, unvouchered).