Homalium oppositifolium Baill.
Creators: name: Wendy L. Applequist
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Malpighiales
Salicaceae
Homalium
Homalium oppositifolium

description: 9. Homalium oppositifolium (Tul.) Baill. in Bull. Mens. Soc. Linn. Paris 1: 575. 1889.
Ξ Myriantheia oppositifolia Tul. in Ann. Sci. Nat., Bot. sér. 4, 8: 65. 1857 [as Myrianthea].
Typus: Madagascar: sine loc., s.d., fl., du Petit-Thouars s.n. (P [P04705657]!; iso-: P [P 04705659]!)
= Homalium fasciculatum Scott-Elliot in J. Linn. Soc., Bot. 29: 21. 1891.
Lectotypus (designated by Sleumer, 1973: 323): Madagascar. Prov. Toliara: Fort-Dauphin, V.18 ??, fl., Scott Elliot 2617 (K [K000231470] image seen; isolecto-, PRE [PRE0602205-0] image seen). Syntypus: Madagascar. Prov. Toliara: Fort-Dauphin, V.18 ??, post-fl., Scott Elliot 2639 (K [K000231471] image seen, P [P04705656]!).
= Homalium lanceolatum Scott-Elliot in J. Linn. Soc., Bot. 29: 23. 1891. Typus: Madagascar. Prov. Toliara: Fort-Dauphin, s.d., fl., Scott Elliot 3056 (holo-: K [K000231472] image seen; iso-, P [P04705661]!, L [L0010982] image seen).
= Homalium cymosulum Scott-Elliot in J. Linn. Soc., Bot. 29: 22. 1891. Typus: Madagascar. Prov. Toliara: Fort-Dauphin, VII.18 ??, fl., Scott Elliot 3037 (holo-: K [K000231469] image seen; iso-: P [P04705658]!) [Hybrid of H. oppositifolium × H. trigynum].
Tree to 20 m tall, 40(-80) cm dbh, with smooth whitish bark; large twigs grayish to brown; young twigs brown to tan, short-pubescent to glabrous; stipules linear to narrowly deltoid or narrowly lanceolate, (1-) 1.5-3 mm, shortpubescent. Leaves mostly opposite; petiole 2-6(-10) mm, short-pubescent (especially when young) to glabrous; blade elliptical to broadly elliptical (narrowly elliptical or oblongelliptical, obovate, very rarely oblanceolate), 4.2-7.2(-9.5) × 1.8-3.5(-5) cm; base rounded to convex (cuneate, probably only when young); apex rounded (to apiculate, short-attenuate, emarginate, obtuse to acute); margins serrulate at least basally (to subentire), often somewhat revolute, with glands usually borne in small teeth, sometimes absent or only 2 or 3; abaxial surface short-pubescent on midrib (seldom on other veins or surface), often becoming glabrous, drying brown; adaxial surface glabrous (short-pubescent along midrib), drying darker brown than abaxial surface. Inflorescences racemose with flowers often opposite or clustered, lateral, (1.5-)4-10(-14) cm, densely (moderately) short-pubescent (rarely glabrate distally); peduncle 0.3-3 cm, moderately thick; pedicel 1-4(-6.5) mm, densely pubescent with crinkly hair; bracts occasionally numerous on lower part of rachis, ovate to elliptical, lanceolate or oblong (broadly ovate to broadly oblong), (1-)1.7-3(-4.5) mm, usually densely pubescent; bracteoles lanceolate to oblong-elliptical, 1-3(-4.4) mm, usually densely pubescent. Flowers: sepals 5-6, white to pale or yellowish green, oblong-ovate to narrowly elliptical or elliptical, narrowly oblong-elliptical, or oblanceolate with rounded to acute apex, (2.6-) 3-6 mm, abaxial surface pubescent with appressed and protruding crinkly hairs, less so near apical margin, adaxial surface also sometimes sparsely pubescent; calyx cup funnelform (sometimes to cup-shaped or cylindrical), pubescent; sepal glands yellow (ringed with orange, or with dark guides), broadly elliptical (oblong), sometimes prominently elevated on pubescent stalk, 0.6-1 (-1.4) × 0.4-0.7 mm, upper surface short-pubescent (sometimes minutely or only in the center); petals white, obovate (oblanceolate) with rounded apex, (3-)3.4-7.3 × 1.3-2.8 mm, moderately longer than sepals, abaxial surface densely to moderately, mostly appressed long-pubescent (less pubescent along apical margins), adaxial surface sparsely pubescent or glabrous; stamens normally 3 per fascicle (aberrantly in part 4 per fascicle); filaments white or pale pink, 2.4-4 mm, glabrous or sparsely villous; anthers red to reddish brown or purple, 0.2-0.4 mm; ovary more or less conic, densely pubescent; styles 3(-4), (1-) 1.6-2.4 mm, basally pubescent. Seeds probably 1 per fruit, to 1.2 mm (mature seeds not seen).
Vernacular names and uses. – “Fotsivony” (Service Forestier 5627); “Hazomalany” (Birkinshaw et al. 333); “Hazombato” (Service Forestier 21905); “Hazombatondrano” (Service Forestier 4805); “Hazompoza” (Service Forestier 8014, 9412, 16446); “Hazondrano” (Service Forestier 14475); “Hazondroka” (Service Forestier 9743); “Hazontreka” (Service Forestier 6126); “Hazopoza” (Service Forestier 14747); “Iatongoro” (Réserves Naturelles 4757); “Ioharia” (Réserves Naturelles 7461); “Karaka” (Louvel 76); “Lalimboay” [Bara dialect] (Service Forestier 2238); “Rohandria” (Service Forestier 5327, 9743); Samanta (Service Forestier 14429); “Sana” (Decary 5044); “Tadolo [?]” (Decary 5127); “Tafaran” (Cloisel 230); “Tanteliravina” (Service Forestier 12284, 14461); “Tateliravina” (Service Forestier 14414); “Tsitakonala” [Betsimisaraka dialect] (Service Forestier 10566, 17711, 18159); “Tsitakonala à p.f. [petits feuilles]” (Service Forestier 10821); “ Tsitakonalafotsy” (Service Forestier 14176); “Tsivalandra” (Réserves Naturelles 3814); “Vatongero” (Réserves Naturelles 4734).
The wood of H. oppositifolium is used for construction, for manufacture of wooden objects including fence stakes, and as firewood (Cloisel 230; Service Forestier 16446, 17711, 21905). Flowers are said to be sweet-scented (Nikolov 1848).
Distribution, ecology and conservation status. – Homalium oppositifolium occurs in low- to mid-elevation humid forests and in littoral or marsh forests, and very rarely extending into dry deciduous forest; it is reported on sand, gneiss, and clay. Though sometimes described as locally rare, it is widespread; hence the preliminary conservation status assessment is “Least Concern” [LC].
Notes. – There is only one complete herbarium specimen of the type collection of H. oppositifolium at P, which can be considered the holotype; the second sheet comprises only fragments in two paper packets. As for H. laxiflorum, above, Sleumer (1973: 323) stated that the type came from Foulpointe, though its label included no locality data. Du Petit-Thouars collected both on the coast near Fénérive (including Foulpointe) and around Fort-Dauphin (Dorr, 1997: 346). Homalium oppositifolium is found at both of those locations, but since the bracts on the type specimen are not particularly large (see discussion below), it is more likely to have been collected from the region of Fénérive.
Homalium oppositifolium is distinguished by its small, opposite leaves and very pubescent flowers, with perianth indument often extending to the adaxial surfaces of sepals and petals. Several specimens from the region around Fort-Dauphin, at the southeastern extreme of the species’ distribution, have enormous bracts and bracteoles, more than twice the typical length of those on more northerly specimens and unusually broad. Since some intermediate sizes are observed, and no other obvious characters were noted that consistently separate Fort-Dauphin populations from others, this is considered to be a local variant rather than a distinct taxon to be recognized under one of Scott-Elliot’s previously published names. However, further study of the populations in this area would be desirable.
Homalium cymosulum was published based on Scott Elliot 3037, a reddish-flowered collection from Fort-Dauphin with a cylindrical calyx cup. The P isotype appears to be identifiable as a hybrid of H. oppositifolium × H. trigynum.
Kotozafy & Rasabo 862 (MO, P) from Ranomafana has densely pubescent glands and some resemblance to Homalium oppositifolium, but the leaves are alternate and the sepals are much shorter than the petals and very weakly pubescent. Service Forestier 17711 (P) comes from the coastal locality of Tampolo; it has short-acuminate leaves, small long-stalked glands, and very weak gland and perianth indument. These specimens are suspected to represent hybrids, but the identity of the other parent is uncertain.
Additional material examined. – Madagascar. Prov. Antsiranana: Ambodivapaza, forêt de Farahangitra, 14°08’20”S 49°54’50”E, 315 m, 12.IV.2013, fl., Rakotonirina et al. 122 (G, K, MO); canton Marovato, district Ambanja [probably Tsaratanana RN], 13.XII.1952, fl., Réserves Naturelles 4734 (P); ibid. loc., same date, fl., Réserves Naturelles 4757 (P). Prov. Fianarantsoa: Midongy du Sud, National Park buffer zone, 23°36’41”S 47°02’05”E, 577 m, 23.VIII.2008, post-fl., Bussmann et al. 15112 (MO, P); Vangaindrano, edge of Midongy du Sud NP, Ambalabe Forest, 23°36’08”S 47°02’58”E, 687- 775 m, 23.VIII.2008, post-fl., Bussmann et al. 15127 (MO, P); Vondrozo, 17.VI.1925, fl., Decary 3852 (P); Midongy du Sud, 21.VIII.1926, post-fl., Decary 5044 (P); ibid. loc., same date, fl., Decary 5127 (MO [3 sheets], P); Prov. de Farafangana, 23.VIII.1926, post-fl., Decary 5151 (MO, P); Vallée de l’Itomampy, VI.1919, Perrier de la Bâthie 12654 (P); RN 25, 7 km W of Ranomafana town, 21°15’S 47°25’E, 600-900 m, 14.VI.1994, fl., Randrianasolo et al. 63 (MO); 2 km W d’Andrambovato, bord de la rivière Tatamaly, 21°30’S 47°24’E, 1075 m, 19.X.2000, fl., Randriantafika 170 (MO, P); Farafangana, rivière Tohakondra, 6.XI.1950, fl., Service Forestier 2238 (P); Fianarantsoa, Fort-Carnot, Sahavia, 30.VI.1951, post-fl., Service Forestier 4805 (P); Farafangana, Manombo, 11.VII.1952, fl., Service Forestier 5627 (P); Ambohimanga du Sud, Ambaro, 17.XI.1952, fl., Service Forestier 7049 (P); env. du Manombo, au S de Farafangana, 26.VI.1954, Service Forestier 9201 (P); Andrambovato, 30.VII.1954, post-fl., Service Forestier 12284 (P); Fort-Carnot, Andrambovato, parcelle B-8, 10.VI.1954, fl., Service Forestier 14414 (P); Mananjary, Amboropotsy, 16.V.1954, fl., Service Forestier 14429 (P); Andrambovato, 12.VI.1954, Service Forestier 14461 (P); Mananjary, Ifanadiana, 1.VI.1954, fl., Service Forestier 14475 (P); Androrangavola, Ifanadiana, 21.IV.1954, post-fl., Service Forestier 14544 (MO, P); Nosy-Varika, Ampasinambo, Antanifotsy, 9.X.1954, fl., Service Forestier 14747 (P); Farafangana, Anjorozoro, 4.IV.1966, fl., Service Forestier 25853 (MO, P). Prov. Mahajanga: Ambodiriana, rive droite du fleuve, 700 m, 14.XII.1944, fl., Cours 1957 (MO, P); Ambendraria, forêt d’Ampoakafobe, à 6 km W du village d’Antsiatsiaka, 16°01’34”S 49°04’19”E, 769 m, 8.XI.2004, fl., Lehavana et al. 190 (MO, P); Antsakoabe, formation sur le lavaka Antakoanibata, Tsingy Beanka, 18°05’48”S 044°31’57”E, 211 m, 21.XI.2012, fl., Rakotovao et al. 6323 (MO). Prov. Toamasina: Fkt. Anjiahely, 15°24’00”S 49°26’12”E, 740 m, 14.XII.2002, post-fl., Antilahimena et al. 1476 (MO, P); ibid. loc., 15°23’04”S 49°26’58”E, 1005 m, 20.XII.2002, post-fl., Antilahimena et al. 1534 (MO, P); Soanierana Ivongo-Ampasimbola, 50 m SE of track, PDOP 2.5, 16°57’26”S 49°33’55”E, 60 m, 3.VII.1996, fl., Birkinshaw et al. 333 (MO, P); Antanambao, river Antsohihy, 16°47’18”S 49°41’54”E, 58 m, 30.VI.2007, fl., Birkinshaw & Andriamiarinoro 1755 (MO); Ambatondrazaka, bords de la Mahamaro, Anosibe, 700 m, XI.1938, fl., Cours 866 (P); Tampina, 25.VIII, fl., Louvel 76 (P); Pointe à Larrée, fkt. Ambohitsara/Ampeny, forêt de Menagisy, 16°46’30”S 49°40’45”E, XI.2008, Nikolov 1848 (MO); Haut Anosivola, bassin du Mangoro, XI.1911, fl., postfl., Perrier de la Bâthie 6711 (P); [Analamazaotra] vers 1000 m alt, X.1922, Perrier de la Bâthie 15476 (P); Fénérive-Est, Tampolo forestry station, along the “ Grand Layon ” towards the ocean, 17°17’S 49°23’E, 5 m, 31.VII.1996, fl., post-fl., Randrianasolo 451 (MO, P); Ambinanitelo, forêt d’Anjiabe, limite entre Befandriana Nord et Maroantsetra, suivant la piste vers Andranomena Mantsoandakana, 15°35’S 49°23’E, 17.II.2008, fl., Ravelonarivo et al. 2879 (MO); Moramanga, Sahanomby, 4.VII.1952, sterile, Service Forestier 6126 (P); Marolambo, Ambalamena, 13.XII.1953, fl., Service Forestier 8014 (P); ibid. loc., same date, fl., Service Forestier 9412 (P); Tampolo, 112 bis JB. 21, 1.VI.1954, fl., Service Forestier 10506 (P); Tampolo, 24.IX.1954, fl., Service Forestier 10821 (P); ibid. loc., 16.V.1955, post-fl., Service Forestier 14176 (P); district Marolambo, Morafeno, côté gauche du chemin, 29.X.1956, Service Forestier 16446 (P); Tampolo, 28-29.VIII.1957, fl., Service Forestier 18150 (P); Distr. Vavatenina, Ampasimazava, Nosibe, 3.IX.1964, fl., Service Forestier 21905 (P). Prov. Toliara: Route de Fort-Dauphin à Mahakalaky, s.d., fl., Boiteau 2141 (MO, P); Fort-Dauphin, s.d., fl., Cloisel 230 (P); ibid. loc., 15.VI.1926, fl., Decary 4027? (P); ibid. loc., 8.VII.1926, fl., Decary 4270 (MO, P); Mandena 7.5 km N of Fort-Dauphin, 24°58’S 46°59’E, 0-10 m, Gereau et al. 3295 (MO, P); forêt de Manantantely près Fort-Dauphin, 50-300 m, 1.III.1947, Humbert 20380 (P); Antsotso, TGK 42, forêt de Bemangidy, 24°35’17”S 47°08’42”E, 28 m, s.d., fl., Randriatafika 861 (MO); Fort-Dauphin, Ifarantsa, 24.IV.1952, fl., Réserves Naturelles 3814 (MO [2 sheets], P); ibid. loc., 25.V.1955, fl., Réserves Naturelles 7461 (P); Fort-Dauphin, May, postfl., Scott Elliot 2639 (P); Mandena, 11.VI.1952, fr., Service Forestier 5327 (P); Fort-Dauphin, Andreò, 2.IV.1954, fl., Service Forestier 9743 (P).
description: Published as part of Wendy L. Applequist, 2016, Revision of the Malagasy species of Homalium sect. Eumyriantheia Warb. (Salicaceae), pp. 33-60 in Candollea 71 (1) on pages 48-50, DOI: 10.15553/c2016v711a7, http://zenodo.org/record/161516