Homalium confertum Baker

Wassel, Anna C. & Applequist, Wendy L., 2020, A revision of Homalium sect. Nisa (Salicaceae) endemic to Madagascar, Candollea 75 (1), pp. 1-23 : 6-8

3. Homalium confertum Baker in J. Linn. Soc., Bot. 21: 341. 1884 ( Fig. 1 ).

Lectotypus (designated by SLEUMER, 1973: 298): MADAGASCAR: “ Central Madagascar ”, s.d., fr., Baron 3185 ( K [ K000231489 ] image seen; isolecto-: BM, L [ L0010973 ] image seen, P [ P00418088 ]!) . Syntypus: MADAGASCAR: “Central Madagascar”, s.d., fr., Baron 3256 ( K [ K000231490 ] image seen) .

Tree to 22 m tall, 60 cm dbh; bark exfoliating in plaques; twigs gray to medium brown, glabrous, leafing internodes (1.2–)1.7–4(–5)mm diam.; stipules fused, sometimes persistent. Leaves elliptic to oblong-elliptic, narrowly or broadly elliptic, or obovate, (5–)6– 16 × (1.8–)3– 6.2(–7) cm; base convex to cuneate; apex cuspidate, obtuse, acute, or rounded (shortacuminate); margin serrate to dentate or slightly crenate, rarely nearly entire, glands in tooth apices elongated and relatively conspicuous; secondary veins 8–14(–16) per side, sometimes with similar intersecondary veins; both surfaces glabrous (aberrantly bearing patches of short trichomes, possibly pathogenic), or abaxial surface moderately glaucous, drying medium to dark brown on both surfaces (rarely light green); petiole 3–7(–10) mm, glabrous. Inflorescences racemose, axillary (often paired), (2–)4–8.5(– 11) cm; rachis glabrous (sparsely shortpubescent or more densely so in irregular patches); bracts and bracteoles (1.5–) 2–4 mm, glabrous except margins of bracts usually ciliate; flowers borne singly. Flowers 5–6-merous, white to green or yellow-green; sepals 3–7 mm in flower, 8–12.5 mm in fruit, oblanceolate to spatulate or narrowly oblanceolateoblong, adaxial surface usually glabrous (midrib sometimes sparsely short-pubescent), abaxial surface usually glabrous (sparsely short-pubescent at base); sepal glands yellow, glabrous; petals ovate, 2–4 mm, both surfaces densely (to moderately) pubescent especially on apical half; filaments glabrous (sparsely pubescent on the basal portion), 1.7–3.1 mm; anthers (0.45–) 0.5–0.6 mm; styles 1.5–2.5 mm.

Vernacular names and use. – “Hazombato” (Razafindramora 1, Ser vice Forestier 1776, 25277); “Hazombatofotsy ” (Razanatsima et al. 1136, Service Forestier 7362, 16801, 25277); “Lalondalitra” (Service Forestier 15406); “Longotra-fotsy” (Service Forestier 1249); “Marankoditra” (Réserves Naturelles 6043, Service Forestier 25277); “Tsianihiposa” (Service Forestier 10148).

Wood is used to make unspecified products (Service Forestier 25277).

Distribution, ecology and conservation status. – Homalium confertum is widespread in eastern and central regions of Madagascar. It usually occurs in humid forests at mid- to high elevations (range 445–1860 m), but also extends into relatively dry western forests (Ankarafantsika). Reported substrates include gneiss. It is sometimes common and locally dominant (Randrianaivo et al. 526). It has been collected in several protected areas, including Ambohitantely, Anjanaharibe-Sud, Ankarafantsika, Montagne d’Ambre, and Zahamena. Its conservation status is estimated as “Least Concern” [LC].

Notes. – Homalium confertum was lumped into H. nudiflorum by SLEUMER (1973). It differs from H. nudiflorum s.s. in its larger, often strongly toothed leaves with many marginal glands and its more densely pubescent petals; the final perianth size may also be larger. The two overlap in range, but H. confertum is more tolerant of dry climate and high altitude, with much of its habitat on the central plateau. It is similar to H. pachycladum and H. retusum , which also overlap in range, in maximum leaf size, but H. pachycladum and retusum are distinguished by entire leaf margins, fewer leaf glands, and petals glabrous on the abaxial surface.

Several possible hybrids between H. confertum and H. nudiflorum are seen in two regions where both are known, and gene flow is suspected to be responsible for some of the range of variation in H. nudiflorum ; these are discussed under the latter species. Hybridization is seen in most sections of Homalium , even rarely among species of different sections ( APPLEQUIST, 2018b), so the ability of these species to hybridize does not suggest that they should not be recognized as distinct, given their significant morphological and ecological differences.

Additional material examined. – MADAGASCAR. Reg. Alaotra-Mangoro [Prov. Toamasina]: PN Zahamena, 17°38'25"S 48°38'34"E, 989 m, 30.III.2000, buds, Ratovoson et al. 184 ( MO, P) ; Manaka, Ambatondrazaka , 20.II [?].1953, fl., Reserves Naturelles 6043 ( MO) ; P. K. 39 route d’Anosibe, canton and souspréfecture Anosibe , 4.V.1965, fr., Service Forestier 25277 ( P) . Reg. Amoron’i Mania [Prov. Fianarantsoa]: commune d’Ambalamanakana , 20°44'01"S 47°11'42"E, 1860 m, 27.III.1996, fl., Rakotomalaza et al. 681A ( MO, P) . Reg. Analamanga [Prov. Antananarivo]: Tampoketsa-Ankazobe , RS Ambohitantely , 18°11'52.5"S 47°17'3"E, 1620 m, 7.III.2004, fl., Almeda et al. 8636 ( MO) ; Anjozorobe, commune d’Ambongamarina, Andreba , 18°16'55"S 47°54'24"E, 1400 m, 11.III.2000, fl., Randrianaivo et al. 526 ( MO) ; Ambohitantely RS , 18°11'46"S 47°17'24"E, 1620 m, 12.III.1997, Ravololonanahary et al. 69 ( MO) . Reg. Analanjirofo [Prov. Toamasina]: Beanana , 700 m, 22.II.1954, fl., Service Forestier 9058 ( MO, P [2 sheets]) . Reg. Anosy [Prov. Toliara]: Antsotso Avaratra , forêt Tsitongambarika , 24°34'S 47°12'E, 2.IV.2008, fr., Razakamalala et al. 4148 ( MO, P) . Reg. Atsinanana [Prov. Toamasina]: Ambodilendemy, Ankerana , 18°25'49"S 48°47'14"E, 890 m, 24.III.2011, fl., Antilahimena 7778 ( MO) ; Ambodilendemy, vers le sommet d’Ankerana , 18°25'49"S 48°47'14"E, 900m, 14.III.2011, fl., Ravelonarivo & Felix 3663 ( MO) ; Vatomandry, Ambalabe , 19°09'27"S 48°34'57"E, 596 m, 11.III.2013, fl., Razanatsima et al. 1136 ( BR, G, K, MO, USMS) . Reg. Boeny [Prov. Mahajanga]: Réserve Naturelle Intégrale d’Ankarafantsika , 16°18'00"S 46°49'00"E, 22.IV.1994, fl., Rajemisa 24 ( MO) . Reg. Bongolava [Prov. Antananarivo]: Tsiroanomandidy , Ambaravaranala , 18°25'S 45°40'E, 1190–1200 m, 25.VI.1997, fl., Rakotomalaza et al. 1353 ( G, MO). Reg. DIANA [Prov. Antsiranana]: Montagne d’Ambre (partie N.O.), 1000–1800 m, 23.XII.1967, fr., Bernardi 12003 ( MO, P); contreforts occidentaux du Massif de Marojejy ( NE) près du col de Doanyanala (limite des bassins de la Lokoho et de l’Andraronga), 800–1200 m, 25.I–25. II.1949, fl., Humbert 23040 ( P [3 sheets]); montagnes au N de Mangindrano (haute Maevarano) jusqu’aux sommets d’Ambohimirahavavy (partage des eaux Mahavavy-Androranga), 1500 m, 19.I–12.II.1951, fr., Humbert & Capuron 24888 ( P); flanc S du M. Tsaratanana, 1700 m, XII.1912, fl., Perrier de la Bâthie 6705 ( P). Reg. Haute Matsiatra [Prov. Fianarantsoa]: Ampamaherana, Fianarantsoa, 13.XII.1949, fl., Service Forestier 1249 ( P). Reg. SAVA [Prov. Antsiranana]: Daraina, forêt d’Antsahabe , 13°13'03"S 49°32'46"E, 780 m, 2.XII.2004, fr., Gautier 4806 ( MO, P); Ampasindava , forêt de Bongomihirahavavy , 13°46'11"S 48°04'58"E, 445 m, 4.XII.2013, fr., Gautier et al. 6092 ( G, P); massif de l’Anjanaharibe (pentes et sommet N) a l’W d’Andapa (haute Andramonta, bassin de la Lokoho: NE), 1600–1800 m, 10.XII.1950 – 3.I.1951, fl., Humbert et al. 24704 ( P); Doany, Anjialavahely , 14°17'41"S 49°32'50"E, 949 m, 15.III.2006, fl., Rakotovao et al. 2986 ( MO, P); Anjialavabe, Ankiakabe , 14°10'47"S 49°22'01"E, 1567 m, 23.II.2007, fl., Ravelonarivo et al. 2238 ( MO, P); Antalaha, Bealampona , village de Befingotra , 14°45'11"S 049°28'49"E, 762 m, 21.IV.1997, fl., Razafindramora 1 ( MO). Reg. Sofia [Prov. Mahajanga]: Marsoandakana , 14°55'39"S 49°25'52"E, 1176 m, 23.II.2008, fl., Bernard et al. 876 ( MO); NW du campement Bemafo, 14°13'17"S 49°03'55"E, 1830 m, 26.X.2005, fl., Buerki et al. 106 ( MO, P). Reg. Vakinankaratra [Prov. Antananarivo]: Angodona, Tsinjoarivo, 6.VI.1950, fl., Service Forestier 1766 ( P [2 sheets]). Reg. Vatovavy-Fitovinany [Prov. Fianarantsoa]: Ampasinambo , Nosy-Varika , 21.IV.1954, fl., fr., Service Forestier 10148 ( MO, P).

Figures

Fig. 1. – Flower of Homalium confertum Baker post-anthesis. [Buerki 106] [Photo: S. Buerki]