Homalium thuarsianum (Tul.) Baill.

Applequist, Wendy L., 2018, A revision of the Malagasy species of Homalium sect. Blackwellia (Salicaceae), Candollea 73 (2), pp. 221-244 : 240-241

14. Homalium thuarsianum (Tul.) Baill. , in Bull. Mens. Soc. Linn Paris 1: 574. 1886 [as thouarsianum].

≡ Blackwellia thuarsiana Tul. in Ann. Sci. Nat., Bot. ser. 4, 8: 60–61. 1857.

Holotypus: MADAGASCAR: sine loco, s.d., fl., du PetitThouars s.n. ( P [ P04679701 ]!; isotype: L [ L0011030 ] image seen).

Tree to 20 m, 41 cm dbh; young twigs glabrous. Leaves oblanceolate to obovate (oblong-oblanceolate, elliptical), (2.8 –)3.5 – 7.8(– 10) × (1.2 –)1.6 – 3.8(– 5.2) cm; petiole (0 –)2– 5(–6) mm; base cuneate to convex; apex rounded to somewhat obtuse or acute with rounded apex (shallowly emarginate, rounded-cuspidate); margins entire or subentire, sometimes revolute, occasionally slightly repand, with glands absent or few and sunk in margins; adaxial surface drying grayish to dark (greenish) brown, abaxial surface brown. Inflorescences paniculate usually with well-developed branches, lateral (pseudoterminal), (4–)6.7–17(–20) cm, moderately to densely pubescent with fine white, usually erect hairs, to short-pilose; flowers pedicellate with pedicels 1–2.7 mm; bracts ovate to broadly elliptical (linear), (0.8–)1.5– 2.5 (seldom foliose, to 22 mm). Flowers 7–9-merous; calyx tube subcylindrical with rounded base, pubescent with erect white hairs to pilose; sepals ligulate with acute apex, 1.5–4.2 mm; petals ligulate with acute apex, 1.6–4.5 mm; sepals and petals variable in color, greenish-white to yellowish, cream or beige, pink to red or purple probably in fruit, accrescent, longer than calyx tube, almost always ascending (some flowers spreading at anthesis, apparently returning to ascending in fruit), ciliate with hairs very long near apex, abaxial surface appressed-pubescent (rarely sparsely pilose), adaxial surface sparsely pilose; sepal glands sparsely pilose to sparsely pubescent; filaments 0.8– 1.7 mm, pilose; ovary sparsely to moderately pilose; styles (4)5, (0.6–) 0.8–1.3 mm, pilose at base.

Vernacular names and uses. – “Hazobato” (Service Forestier 2875); “Hazombato” (Lehavana & Zackarie 711, Noyes et al. 960, Rabevohitra et al. 4370, 4610, 4864, 4970, Réserves Naturelles 10340, Service Forestier 4603, 5861, 8314, 9525, 15701, 19526); “Hazombato à g[randes] f[euilles]” (Service Forestier 15701); “Hazombato à p[etites] f[euilles]” (Service Forestier 15172); “Hazombato-mena à p[etites] f [euilles]” (Service Forestier 15702); “Hazondrano-fotsy” (Service Forestier 15704); “Maraokoditra” (Service Forestier 14228); “Tsitakonala” (Service Forestier 4153).

Wood of H. thuarsianum is used for construction (Service Forestier 19526).

Distribution, ecology and conservation status. – Homalium thuarsianum is native to littoral and sublittoral forests along the eastern coast of Madagascar; it is reported on sand. One specimen (Antilahimena & Felix 7756) was collected at 1053 m altitude, geographically relatively close to the species’ range but far outside its normal altitude range; this specimen cannot be excluded from the species by morphology. Though the habitat is fragmented and highly threatened, this species is relatively widely distributed and occurs in the protected areas of Tampolo, Soanierana-Ivongo, Nosy Mangabe, and Masoala. Therefore its conservation status is estimated as “Least Concern” [LC].

Notes. – Homalium thuarsianum is the most widespread and common of three species with pubescent sepal glands and usually well-developed paniculate inflorescences, the other two being the newly described H. fortunatii and H. martialii . All three share other features in common, including often relatively large bracts, 7–9-merous flowers, and sepals and petals that are usually pubescent on the abaxial surface (in H. thuarsianum , occasionally sparsely pilose) but somewhat pilose to villous on the adaxial surface. They are all native to low-altitude eastern humid forests. This author considers it reasonable to presume that they are a natural group. The distinctions between H. thuarsianum and the other two species of this group are described under those species.

Flowers are visited by bees (Lehavana et al. 54, Ludovic & Rakotoarivony 241).

Selected material examined. – MADAGASCAR. Prov. Fianarantsoa : Fkt. Ambahy , forêt d’Andohan’I Martin , 20°48'07"S 48°28'56"E, 22 m, 13.XI.2003, fl., Rabehevitra et al. 749 ( MO, P) ; Fkt. Ambahy , 20°46'15"S 48°28'48"E, 21.III.2003, fl., Rabevohitra et al. 4610 ( MO, P) ; Entre Vohipeno et la mer , VII.1954, fl., Service Forestier 9221 ( P) ; Ankijy, Vatomasina, Vohipeno , 13.IX.1956, fl., Service Forestier 14228 ( P) ; Ankazondratana, Nosy Varika , 30.V.1958, fl., Service Forestier 19526 ( P [2 sheets]) . Prov. Toamasina : Brickaville , fkt. Ambodilendemy , Ankerana , 18°24'58"S 48°47'21"E, 1053 m, 23.III.2011, fl., Antilahimena & Felix 7756 ( MO, P) ; Mananara , 28.IX.1920, fl. & fr., Decary 63 ( P) ; Ambila-Lemaitso , 18°49'S 49°09'E, 2–5 m, 15.XI.1989, fl. & fr., Keating & Miller 2261 ( MO, P) ; Tampolo , 17°17'16"S 49°24'30"E, 16 m, 14.IV.2004, fl. & fr., Lehavana et al. 54 ( MO, P) ; Fkt. Tanambao Ambodimanga , près du gite , 16°47'S 49°43'E, 27.V.2010, fr., Lehavana & Zackarie 711 ( MO) ; Île Sainte-Marie, Lokintsy , forêt d’Ambohidena on NE coast , 16°51'11"S 49°57'10"E, 10 m, 13.V.2003, fr., McPherson et al. 18913 ( MO, P) ; 9.4 km W of Mahavelona village ( Foulpointe ), 17°38'S 49°30'E, 10 m, 28.II.1992, Noyes et al. 960 ( MO) ; Fkt. Ambohidena , forêt d’Ambohidena , 16°51'05"S 49°57'13"E, 10 m, 10.X.2003, fl., Rabehevitra et al. 654 ( MO, P) ; Cne rurale Manompana , Forêt Antanambao-Ambodimanga , 16°45'40"S 49°42'35"E, 1.II.2003, fl., Rabevohitra et al. 4370 ( MO, P) ; Andranokoditra , Ankanin’ny nofy , forêt de Vohibola , 18°35'42"S 49°14'02"E, 10.II.2003, fl., Rabevohitra et al. 4413 ( MO, P) ; Soanierana-Ivongo, Andrangazaha , 16°52'02"S 49°40'52"E, 29.1.2004, fl., Rabevohitra & Rakotomamonjy 4864 ( MO, P) ; Forêt au NW de Tanambao , 16°45'12"S 49°42'56"E, 31.I.2004, fr., Rabevohitra et al. 4970 ( MO, P) ; Fkt. Ambohidena , forêt d’Ambohidena , 16°51'11"S 49°57'18"E, 18.II.2004, fl., Rabevohitra et al.5016 ( MO, P) ; Tampini , X.1924, fl. & fr., Réserves Naturelles (Dumazer) s.n. ( P) ; RN II [ Masoala ], Ambohitralalana, district Antalaha , 16.II.1954, fr., Réserves Naturelles 6620 ( P) ; Soanierana-Ivongo , 18.V.1959, fl. & fr., Réserves Naturelles 10340 ( P) ; Nosy Mangabe RS 4–5 km S of Maroantsetra, 15°30'S 49°46'E, 0–330 m, 21.II.1992, fr., Schatz et al. 3243 ( MO, P) ; Gare d’Ambila-Lemaitso , 28.VIII.1951, fl. & fr., Service Forestier 4153 ( P) ; Antetezana, Tamatave , 28.XII.1951, fl. & fr., Service Forestier 4603 ( P) ; Ambila-Lemaitso , 10.X.1953, fl., Service Forestier 5861 ( P) ; S de Tenina , S de Rantabe , IV.1954, fl. & fr., Service Forestier 9168 ( MO, P) ; Tampolo, Fénérive , 29.VIII.1955, fl., Service Forestier 15172 ( MO, P) ; Tampolo, Fénérive , 22.II.1956, fl., Service Forestier 15701 ( MO, P) ; Île Sainte-Marie, forêt d’Ampaniny , 17.V.1969, fr., Service Forestier 28858 ( P [2 sheets]) .