Malesian Euphorbiaceae Descriptions

96. SUMBAVIOPSIS (Euphorbiaceae)

P.C. van Welzen

Welzen, P.C.  van. 1999. Revision and Phylogeny of subtribes Chrozophorinae and Doryxylinae (Euphorbiaceae). Blumea 44: 411–436.

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Genus description

Species description

Sumbaviopsis J.J.Sm.

    Sumbaviopsis J.J.Sm., Meded. Dept. Landb. Ned.-Indië 10 (1910) 356; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.vi (1912) 13; Gagnep. in Lecomte, Fl. Indo-Chine 5 (1925) 418; Backer & Bakh.f., Fl. Java 1 (1963) 477; Airy Shaw, Kew Bull. 26 (1972) 341; Whitmore, Tree Fl. Malaya 2 (1973) 132; Airy Shaw, Kew Bull. Add. Ser. 4 (1975) 197; Kew Bull. 36 (1981) 346; Alph. Enum. Euphorb. Philipp. Isl. (1983) 45; G.L.Webster, Ann. Missouri Bot. Gard. 81 (1994) 73; Welzen, Blumea 44 (1999) 426; Radcl.-Sm., Gen. Euphorbiacearum (2001) 148, Fig. 13; Welzen in Welzen & Chayam., Fl. Thailand 8, 2 (2007) 562; G.L.Webster in Kubitzki, Fam. Gen. Vasc. Pl. 11 (2014) 142. — Type: Sumbaviopsis albicans (Blume) J.J. Sm.

(Shrub to) tree, monoecious, but usually only one sex per plant; flowering twigs smooth, very shortly tomentose, with a broad soft pith. Indumentum consisting of stellate hairs and probably simple ones, latter indistinct. Stipules triangular, densely hairy outside except for the probably glandular apex, glabrous inside, early caducous, scars very indistinct. Leaves spirally arranged, simple; petiole relatively long, basally and apically pulvinate, with longitudinal grooves when dry, hairy; blade ovate (to elliptic), papery, symmetric, base peltate, rounded, margin (sub)entire to dentate, with few glands along the margin or on the apex of teeth, apex acuminate to cuspidate, very apex acute, upper surface glabrescent, lower surface very densely hairy, with many dark yellow round glands near the base and along the margins near the nerves; venation pinnate with secondary nerves indistinctly looped and connected near margin, veins scalariform, quaternary veins reticulate. Inflorescences terminal or (pseudo)axillary (see note), pendulous, thyrsoid when staminate, raceme-like when pistillate, single or 2 together, not (or hardly) branching, either with only staminate or pistillate flowers, fruits often only developed at base, then perhaps upper flowers staminate; staminate flowers up to 3 per cymule, pistillate flowers one per cymule; rachis and pedicels with longitudinal grooves when dry, densely hairy. Bracts ovate, outside hairy, inside glabrous. Flowers actinomorphic; pedicels with basal abscission zone; disc absent. Staminate flowers: sepals 3–5, ovate, valvate, outside densely hairy, inside glabrous; petals 4 or 5, ± ovate, much shorter than sepals, membranous, glabrous, apex irregularly truncate; stamens c. 75, free, on a torus, torus wall with longitudinal ribs, apex broadened, convex, with stellate hairs, filaments thread-like, glabrous, anthers basidorsifixed, 2-locular, opening introrse with lengthwise slits; pistillode absent. Pistillate flowers: sepals 5 (6), ovate, imbricate, outside densely hairy, inside glabrous; petals absent; pistil 2- or 3-locular, one ovule per locule, smooth, tomentose; style short, hairy, stigmas apically lobed, below hairy, above with long slender fimbriae, esp. on the lobed parts. Fruits lobed capsules (or not on Borneo), septicidal, later (only apically at first) also loculicidal, outside densely floccose, inside glabrous except for a few hairs at the base, somewhat woody, thin-walled; column with a very large, broadened apex, with hardly any remnants of the septa; septa with a single vein. Seeds usually 2 or 3 per fruit, almost globose except for flat area at attachment; covered by a thin, fleshy sarcotesta; exotesta thin, smooth, mesotesta woody, endotesta fibrous. Embryo straight, with flat cotyledons, endosperm copious.

    Distribution — Monotypic genus, distribution as the species.

    Note — The growth is presumably in flushes, including the inflorescence. When young the inflorescence is terminal and it has a few side-branches. Below the side-branches, normal leaves develop and then the side-branches will appear as axillary inflorescences next to the terminal and pseudo-axillary inflorescence. The latter are infructescences next to which side-branches have developed through sympodial growth, the infructescences are then opposite to the leaves.

Sumbaviopsis albicans (Blume) J.J.Sm.

    Sumbaviopsis albicans (Blume) J.J.Sm., Meded. Dept. Landb. Ned.-Indië 10 (1910) 357; Elmer, Leafl. Philipp. Bot. 4 (1911) 1304; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.vi (1912) 14; IV.147.vii (1914) 424; Merr., Enum. Philipp. Fl. Pl. 2 (1923) 428; Gagnep. in Lecomte, Fl. Indo-Chine 5 (1925) 418, fig. 49: 13–18; Merr., Pl. Elmer. Born. (1929) 156; Airy Shaw, Kew Bull. 14 (1960) 357; Backer & Bakh.f., Fl. Java 1 (1963) 477; Airy Shaw, Kew Bull. 26 (1972) 341; Whitmore, Tree Fl. Malaya 2 (1973) 132; Airy Shaw, Kew Bull. Add. Ser. 4 (1975) 197; Kew Bull. 36 (1981) 346; Alph. Enum. Euphorb. Philipp. Isl. (1983) 45; Welzen, Blumea 44 (1999) 428, Fig. 4, Map 3; in Welzen & Chayam., Fl. Thailand 8, 2 (2007) 562, Fig. 87, Plate XXX: 1. — Adisca ? albicans Blume, Bijdr. (1825) 611. — Rottlera ? albicans (Blume) Hassk., Cat. Hort. Bot. Bogor. (1844) 238, excl. description in note 2. — Croton albicans (Blume) Moritzi ex Rchb.f. & Zoll., Acta Soc. Regiae Sci. Indo-Neerl. 1 (1856) 21; Linnaea 28 (1856) 322; Boerl., Handl. Fl. Ned. Ind. 3, 1 (1900) 283. — Cephalocroton ? albicans (Blume) Müll.Arg., Linnaea 34 (1865) 760; Scheff., Ann. Mus. Bot. Lugduno-Batavum 4 (1868) 120. — Doryxylon albicans (Blume) N.P.Balakr., Bull. Bot. Surv. India 9 (1967) 58, fig. 1–7. — Type: Anonymous s.n. (L, holo, barcode L 0023770), Java, Provinciae Tjanjor.

    Sumbavia macrophylla Müll.Arg., Flora 47 (1864) 482; in DC., Prodr. 15, 2 (1866) 727; Hook.f., Fl. Br. India 5 (1887) 408; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.vi (1912) 12, fig. 2E. — Type: Griffith KD 4791 (K, holo; iso in CAL; photo in L), Myanmar.

    Coelodiscus speciosus Müll.Arg., Linnaea 34 (1865) 154; in DC., Prodr. 15, 2 (1866) 760; Hook.f., Fl. Br. India 5 (1887) 426. — Mallotus speciosus (Müll.Arg.) Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.vii (1914) 205. — Type: Hb. Lenormand (P?, holo, n.v.), India orientalis.

    Sumbaviopsis albicans (Blume) J.J.Sm. var. disperma Gagnep. in Lecomte, Fl. Indo-Chine 5 (1925) 420. — Type: Poilane 10741 (P, holo; iso in UC), Annam, Prov. de Quang-tri, Lang-khoai.

(Shrub to) tree up to 27 m high, dbh up to 20 cm; buttresses absent; flowering twigs 3–5 mm thick, light brown, hairy; young ones white. Outer bark (light) brown to blackish green mottled with whitish green, smooth to scaly; inner bark brown; cambium brown; sapwood white to yellowish brown. Stipules c. 0.6 by 0.4 mm. Leaves: petiole 1.2–11.2 cm long, white; blade ovate (to elliptic), 6.8–37 by 3.2–19 cm, index 1.6–2.6, smooth, peltate by 2–8 mm, dull light to dark green above, greyish white beneath, venation impressed above, raised below, nerves 10–12 per side. Inflorescences grey whitish; pedicels white; buds pale brown; staminate ones up to 16 cm long, pistillate ones up to 38 cm long. Bracts c. 2 by 1 mm. Staminate flowers 8–11 mm in diam.; pedicel c. 2.2 mm long; sepals 4.2–5.8 by 2–3.2 mm, brown; petals 1.7–2.8 by 1.7–2.5 mm, pale green; stamens: filaments 2.5–2.8 mm long, white, anthers 1–1.1 by 0.4–0.6 mm, white to yellow; torus up to 1.4 mm high. Pistillate flowers c. 3.3 mm in diam.; pedicel 2.8–3.5(–4.2 in fruit) mm long; sepals 2.3–4 by 1.5–2.5 mm; ovary 2.7–4.5 by 2.7–3.5 mm wide; style 0.8–1.6 mm long, stigmas spreading, up to 3 mm long with up to the last 1 mm split. Fruits 2.1–3.6 by 1.4–3 cm, bright to dark brown, tomentum light brown; possessing white latex; column 9–25 by 5–13 mm. Seeds 12–20 by 12–15 mm, black; hilum 1.2–2.2 by 2–4 mm. Embryo too young to measure; cotyledons white.

    Distribution — India (Assam, Naga Land, Tripura), Myanmar, Thailand, Vietnam, and Malesia: Malay Peninsula, Sumatra (Aceh, Sumatera Utara), Java, Borneo (Kalimantan Timur, Sabah, Sarawak), and the Philippines (Palawan).

    Habitat & Ecology — Scattered to locally common in primary mixed Dipterocarp forest, gallery forest, dry and/or mixed evergreen forest, secondary forest; in the forest (even with heavy undergrowth), at margins of forest, in open places, along ridges and along streams. Terrain level to hilly. Soil (may be thin) and bedrock: limestone, shale, sandstone, yellow-red loam. Altitude: sea level up to 800 m. Flowering and fruiting more or less the whole year through.

    Uses — The seeds are edible.

    Vernacular names — Thailand: Pang tua phu. Vietnam: A luan ray mang (Gagnepain, 1925). Sumatra: Sempaling (Karo-land). Java: Walih angin. Borneo: Kalimantan: Buantik; Sarawak: Brati (Land Dayak); mantas (Iban). Philippines: Dabdab-balod (Tagbanu) (Elmer, 1911).