Homalium pulchrum Sleumer

Wendy L. Applequist, 2016, Revision of the Malagasy species of Homalium sect. Eumyriantheia Warb. (Salicaceae), Candollea 71 (1), pp. 33-60 : 52

11. Homalium pulchrum Sleumer in Bull. Jard. Bot. Natl. Belg. 43: 320. 1973.

Typus: Madagascar. Prov. Fianarantsoa: Farafangana, Ihorombe , Manombo , 10.I.1955, fl., Service Forestier 12931 (holo-: P [ P00375173 ]! ; iso-: L [ L0010994 ] image seen, P [ P04734398 ]!).

Tree to 22 m tall; large twigs grayish brown; young twigs grayish or dark brown, glabrous; stipules deltoid, ca. 0.5 mm, glabrous. Leaves partly alternate, partly opposite; petiole 3-6(-10) mm, glabrous; blade oblanceolate to elliptical or narrowly elliptical, 4-9(-13.7) × 1.5-3.6(-4.4) cm; base cuneate to convex or attenuate; apex cuspidate to rounded (or acute); margins subentire, seldom minutely revolute (or with few shallow rounded teeth), with 2-4 small glands per side embedded in margins toward base; abaxial surface glabrous, drying medium to pale brown or pale greenish; adaxial surface glabrous, drying dull greenish to grayish. Inflorescences racemose (rarely partly paniculate with a few flowers in small clusters on very short branches), the surviving flowers mostly distal, lateral, 2.3-10 cm, glabrous (sparsely minutely pubescent); peduncle 0.6-5 cm, slender; pedicel 1-2(-2.5) mm, glabrous (sparsely minutely pubescent); bracts lanceolate to deltoid, 0.4-1.5(-2.2) mm, glabrous; bracteoles usually absent. Flowers: sepals 4-5, creamy beige or whitish, narrowly oblong to oblong-elliptical or elliptical with irregularly rounded apex, 2.8-4 mm, abaxial surface glabrous; calyx cup funnelform, glabrous; sepal glands irregularly elliptical, 0.6-1 × 0.4- 0.5 mm, upper surface glabrous and slightly wrinkled; petals white, obovate to lanceolate with rounded apex, (3-)4-6 × 1.5-3.6 mm, usually significantly longer than sepals (rarely equal in length), abaxial surface pubescent with short appressed hairs primarily on central basal portion, with a central darker stripe, adaxial surface glabrous (sparsely pubescent at extreme base); filaments 0.7-1(-2) mm, glabrous; anthers 0.3 mm; ovary conic, densely pubescent; styles 4(-5), 0.5-1.4 mm, basally pubescent. Seeds not seen.

Vernacular names. – “Ropasy” (Service Forestier 13192); “Tsatoky” (Réserves Naturelles s.n.).

Distribution, ecology and conservation status. – Homalium pulchrum is native to low-elevation humid forests in southeastern Madagascar; it is reported to occur on laterite, including laterite of basalt. It is known from only five locations, only one of which is protected; its apparent rarity and the ongoing loss of habitat in most of its range justify a preliminary conservation status assessment of “Endangered” [EN B2ab(iii)].

Notes. – Sleumer (1973) did not note in the protologue of H. pulchrum that two sheets of the type were present at P. However, in this case he labeled only one sheet as the holotype and marked the inferior second sheet as “pars holotypi”, effectively making it an isotype.

Homalium pulchrum is part of the H. capuronii species group (see Table 1 ). It is among two species in that group with normally racemose inflorescences; the other is the distinctive H. schatzii , another species of low-elevation northeastern forests, which has elliptical to obovate leaves, unusual petal indument, and huge sepal glands. It is also notable for often having narrow, oblanceolate to narrowly elliptical leaves and glabrous pedicels and rachises.

Razakamalala et al. 2583 (MO, P) is an atypical specimen with longer leaves and petioles and shorter inflorescences than any other and with petals little longer than the sepals. More typical material has been collected from the same location.

Additional material examined. – Madagascar. Prov. Fianarantsoa: Manombo RS, parcel W of Route Nationale 12, 23°02’S 47°02’E, 100 m, 9-11. III.1991, fl., Schatz et al. 3192 ( P) ; Manombo, 17.X.1964, fl., Service Forestier 23633 ( P). Prov. Toliara: Antsotso, forêt d’Ivohibe , 24°56’22”S 47°20’27”E, 440 m, 2.XII.2005, fl., Razakamalala et al. 2583 ( MO, P) ; ibid. loc., same date, buds, Razakamalala et al. 2586 ( MO, P) ; Antsotso Avaratra , 24°34’03”S 47°11’57”E, 403 m, 10.XII.2007, fl., Razakamalala et al. 3852 ( MO, P) ; ibid. loc., 24°34’16”S 47°12’06”E, 271 m, 8.XII.2007, fl., Razakamalala et al. 3780 ( MO, P [2 sheets]) ; Canton Ampasimena, Editsaky , 22.XI.1949, fl., Réserves Naturelles s.n. ( P) ; Fort-Dauphin, Bemangidy , 31.III.1955, Service Forestier 13192 ( P).