Flora of Thailand Euphorbiaceae

After revision of complete genus (Ottens & Welzen, 20xx) a third species appears to be present in Thailand (Blumeodendron subrotundifolium).

14. Blumeodendron

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Genus description

Identification key

Species descriptions

Blumeodendron

(Müll.Arg.) Kurz, J. Asiatic. Soc. Bengal 42: 245. 1873; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.vii: 47. 1914; Airy Shaw, Kew Bull. 16: 348. 1963; Whitmore, Tree Fl. Malaya 2: 68. 1973; Airy Shaw, Kew Bull. Add. Ser. 4: 57. 1975; Kew Bull. Add. Ser. 8: 37. 1980; Kew Bull. 36: 267. 1981; G.L.Webster, Ann. Missouri Bot. Gard. 81: 77. 1994; Radcl.-Sm., Gen. Euphorbiacearum: 170. 2001; Chayam. in Chayam. & Welzen, Fl. Thailand 8, 1: 130. 2005; G.L.Webster in Kubitzki, Fam. Gen. Vasc. Pl. 11: 125. 2014; Ottens & Welzen, Blumea 61: 66. 2016.

Trees, dioecious. Indumentum: hairs seldom present, small lepidote orange hairs with probably a secreting function present near nodes, inflorescences, young leaves, early caducous. Stipules absent. Leaves alternate to seemingly opposite, often in pseudo-whorls; petiole on both ends strongly pulvinate; blade coriaceous, symmetric, margin entire, with small adaxial extrafloral nectaries near base, along margin and along midrib, penninerved or basally 3- or 5-nerved.  Inflorescences axillary or terminal racemes or panicles. Flowers small, pedicellate; sepals 3–5, valvate; petals absent; disc present. Staminate flowers: disc glands many on dome-shaped receptacle, among stamens; stamens 15–35, free, connective broad with thecae along it, thecae 2-celled; pistillode absent. Pistillate flowers: disc annular; ovary 2- or 3-locular with 1 ovule per locule; style present, stigmas spreading and recurving. Fruits large, tardily dehiscent, thick woody capsules, usually more than 3 cm in diameter, glabrous.

    A genus of 6 species from the Andaman Islands and Burma through Indonesia to the Bismarck Archipelago.  Two species in Thailand. Classification: subfam. Acalyphoideae, tribe Picnocomeae, subtribe Blumeodendrinae.

Key to the species

1. Blumeodendron kurzii  (Hook.f.) J.J.Sm., Meded. Depart. Landbouw 10: 458. 1910; Pax & Hoffm. in Engl., Pflanzenr. IV.147.vii: 47. 1914; Airy Shaw, Kew Bull. 16: 348. 1963; Whitmore, Tree Fl. Malaya 2: 68. 1973; Airy Shaw, Kew Bull. Add. Ser. 4: 57. 1975; Kew Bull. Add. Ser. 8: 37. 1980; Kew Bull. 36: 267. 1981; Chayam. in Chayam. & Welzen, Fl. Thailand 8, 1: 130. 2005; Fl. Thailand 8, 2: 611, Fig. 2. 2007; Ottens & Welzen, Blumea 61: 73. 2016.— Mallotus kurzii Hook.f., Fl. Br. Ind. 5: 427. 1887.— Blumeodendron verticillatum Merr., Philipp. J. Sci. 16: 557. 1920. — Blumeodendron sumatranum S.Moore, J. Bot. 63, Suppl.: 102. 1925. — Blumeodendron cuneatum S.Moore, J. Bot. 63, Suppl.: 103. 1925.

Trees, to 35 m high, branches glabrous; flowering branches 4–22 mm in diam, nodes very thickened. Leaves 3–5-verticillate; petiole 1.3–12 cm long, terete; blade (ovate to) elliptic to oblong to obovate, 8.8–42(–51, see uses) by 4.4–23.7(–26.5) cm, length/width ratio 1.3–2.5, coriaceous, glabrous, base obtuse or cuneate, apex acuminate (to cuspidate) with obtuse tip to 1.5 cm long, extrafloral nectaries often 2, adaxially near base, at both sides along midrib 0–19 and along margin 6–36, usually drying (dark green to) light brown on both sides; nerves (5 or) 6–12 pairs, reticulation obscure, midrib very distinct and rounded benath. Inflorescences cauliflorous, ramiflorous, axillary and terminal, thyrsoid, almost fasciculate; staminate ones more than 8 together, up to 1.7 cm long, pistillate ones c. 4 together, up to 3 cm long; bracts absent. Flowers yellowish, yellow-green or light green; pedicel 0.4–1 cm long; staminate buds globose, c. 35 per inflorescence, c. 3.9 mm diam. Staminate flowers 7–7.5 mm in diam.; pedicel c. 10 mm long; sepals 3, 4–5 by 2.2–3.5 mm; disk lobes yellow; stamens 20–25, filaments 2–10 mm long, yellow, anthers 0.75–1 mm long, yellow to later fulvous. Pistillate flowers not seen; ovary 2- or 3-locular. Fruits capsular, subglobose, 3.3–5.8 cm wide by 2.8–4.6 cm high, dry dark brown; pedicel thickened, c. 1 cm long, c. 6 mm diam., abscission zone in the middle to subapically; sepals usually persistent; disc distinct, drying dark brown; wall 2–4 mm thick, surface knobbly; margin not or slightly thickened as very low ridges; endocarp enclosing two or more seeds; style very sturdy, at most 1 mm long; stigmas usually persistent, up to 5 mm long, spreading. Seeds bean-shaped, but one end smaller than other, 2.1–2.2 by 1.3–1.6 by c. 1.2 cm, dark brown, attached in middle; sarcotesta yellow.

    T h a i l a n d.— PENINSULAR: Ranong (Khlong Wa).

    D i s t r i b u t i o n.— Peninsular Thailand, Malay Peninsula, Sumatra, Java, Borneo, Philippines (Luzon, Samar).

    E c o l o g y.— Ranging from primary and evergreen forest to logged over and secondary forest (with bamboo); soil: often rich, varying from igneous derived sandy soil to sandy clay to loamy soil to limestone; bedrock once reported as basalt. Altitude: 5–600(–1800) m. Flowering: March–August, November–January; fruiting: March–June, August–December.

    V e r n a c u l a r.— Khun thaen (ขุนแท่น) (Narathiwat); ya-ka (ยากา) (Malay-Narathiwat).

    U s e s.— Clemens 51511 (Borneo) is tentatively identified as B. kurzii. It is a single, enormous leaf, c. 51 by 26.5 cm, much larger than all other material of B. kurzii. The label indicates that large leaves are used by the Dusun in N Borneo as rain shelter and to repair leaks in roofs. Seeds eaten in the Philippines.

2. Blumeodendron subrotundifolium (Elmer) Merr., Philipp. J. Sci. 7: 384. 1912; Philipp. J. Sci. 16: 558. 1920; Enum. Philipp. Fl. Pl. 2: 429. 1923; Whitmore, Tree Fl. Malaya 2: 70, Fig. 2. 1973; Ottens & Welzen, Blumea 61: 77. 2016. — Sapium subrotundifolium Elmer, Leafl. Philipp. Bot. 3: 930 (‘subrotundifolia’). 1910. — Blumeodendron subcaudatum Merr., Philipp. J. Sci. 16: 557. 1920. — Blumeodendron calophyllum Airy Shaw, Kew Bull. 19: 309. 1965.

Trees, to 50 m high; flowering branches 3 (staminate)–28 (pistillate) mm diam., nodes somewhat thickened. Leaves alternate to subopposite to in pseudo-whorls; petiole 2.4–18.5 cm long, terete; blade elliptic, 6.2–46 by 3–22 cm, length/width ratio 1.2–3.1, coriaceous (slightly bendable) to very coriaceous (breaking), glabrous, base emarginate to rounded to cuneate, margin recurved, apex acuminate (to cuspidate), extrafloral nectaries on both surfaces along midrib c. 2–26, along margin c. 8–20, adaxial surface usually drying shiny brown, abaxial surface lighter dull brown; nerves 3–4(–11) pairs, reticulation obscure, midrib very distinct and rounded benath. Inflorescences cauliflorous, ramiflorous to axillary, staminate ones often paired, up to 4.5 cm long, pistillate ones single, up to 2.3 cm long, rachis thickening during fruit set to c. 4 mm, peduncle c. 1.3 cm long, brown; bracteoles triangular, c. 0.5 by 0.2 cm, margin undulate. Flowers pale yellow to yellow green to yellowish tinged pink to (greenish) red. Staminate flowers 5–6 mm diam.; pedicel 3–25 mm long, brown; buds 1.5–5 mm diam.; sepals 2 or 3, ovate, 4–5.5 by 3–5 mm; disc lobes yellow; stamens 25–40, yellow, filaments 1.5–3 mm long, anthers 0.4–0.5 mm long. Pistillate flowers not seen; sepals 4 or 5, c. 1.5 by 2.2 mm; ovary 2- or 3-locular, dull sordidly purple; style c. 1 mm long, sturdy, stigmas c. 2.5 mm long, recurved, greenish. Fruits capsular, subglobular (smaller) to ovoid (larger), 3.5–6 cm wide by 2.9–4.5 cm high, green (unripe) to yellow to orange-yellow (or red); pedicel c. 1.5 cm long, to c. 0.8 cm diam., abscission zone in the middle; wall 2–4 mm thick, dark brown when dry, margin slightly thickened, but without ridges, surface knobbly; endocarp enclosing two or more seeds; stigma mostly persistent. Seeds bean-like to flattened at one-side, 2.3–3.4 by 1.6–2.4 by 1.1–1.3 cm, attached in middle; sarcotesta cream to purple.

       T h a i l a n d.— PENINSULAR: Satun (Khlong Ton, Tarutao National Park).

       D i s t r i b u t i o n.— Peninsular Thailand, Malay Peninsula, Sumatra, Java, Borneo, Philippines.

triangles = B. phillipense; dots = B. rotundifolium

       E c o l o g y.— Mixed lowland dipterocarp forest, evergreen forest, gallery (Emperan) forest, peat swamp forest, to mossy submontane forest, along logging roads; soil sandy loam, sandy clay, clayey loam, alluvial soil, bedrock: sandstone. Altitude: sea level to 1200 m. Flowering: March–November; fruiting: January, April–November. Fallen seeds / fruits are eaten by birds and animals (e.g., pigs)

      N o t e.— Blumeodendron subrotundifolium resembles B. kurzii in leaf-shape, colour of dried leaves and leaf texture. However, the leaves do not arise in whorls from thickened nodes. Also, the inflorescences are generally longer than the almost fasciculate ones of B. kurzii.

3. Blumeodendron tokbrai (Blume) J.J.Sm., Meded. Depart. Landbouw 10: 458. 1910; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.vii: 47. 1914; Airy Shaw, Kew Bull. 16: 348. 1963; Whitmore, Tree Fl. Malaya 2: 68. 1973; Airy Shaw, Kew Bull. Add. Ser. 4: 57. 1975; Kew Bull. Add. Ser. 8: 37. 1980; Kew Bull. 36: 267. 1981; Chayam. in Chayam. & Welzen, Fl. Thailand 8, 1: 131. 2005; Fl. Thailand 8, 2: 612, Fig. 3. 2007; Ottens & Welzen, Blumea 61: 78. 2016. — Elateriospermum tokbrai Blume, Bijdr. 12: 621. 1826. — Mallotus tokbrai (Blume) Müll.Arg. in DC., Prodr. 15, 2: 956. 1866. — Rottlera tokbrai (Blume) Scheff., Ann. Mus. Bot. Lugduno-Batavi 4: 122. 1869. — Mallotus ? vernicosus Hook.f., Fl. Brit. India 5: 443. 1887. — ? Elateriospermum paucinervia Elmer, Leafl. Philipp. Bot. 2: 484. 1908. — Blumeodendron elateriospermum J.J.Sm., Bull. Jard. Bot. Buitenzorg, sér. 2, 8: 56, nom. superfl. 1912. — Blumeodendron vernicosum (Hook.f.) Gage, Rec. Bot. Surv. India 9: 244. 1922. — Blumeodendron paucinervium (Elmer) Merr., Philipp. J. Sci. 16 (1920) 555; Enum. Philipp. Fl. Pl. 2: 428. 1923.

Tree, to 40 m high, flowering brances ‒5.5 mm diam., nodes hardly thickened. Leaves usually always a few alternate, but also subopposite to 3 leaves whorled; petiole 1.2–9.4 cm long; blade (ovate to) elliptic (to obovate), 5.3–31 by 3.1–17.3 cm, length/width ratio 1.4‒2.4(‒3.3), pergamentaceous to coriaceous, asymmetric, with simple and lepidote hairs when young, base attenuate to cuneate, margin slightly recurved, apex acuminate to cuspidate, tip rounded to mucronulate, extrafloral nectaries sometimes adaxially along midrib, c. 10, young leaves resinous, covered with orange lepidote hairs, surfaces drying brown to brown-green to dark green, abaxial surface browner than adaxial surface when dry; nerves 5‒9 pairs, prominent beneath, reticulation often distinct. Inflorescences axillary and terminal, staminate ones 1–3 together, to 20 cm long, c. 1.4 mm diam., pistillate ones single, to 10 cm long, c. 1 mm diam.; lepidote hairs orange, simple hairs white. Buds c. 3 mm diam. Staminate flowers 4–7.7 mm diam., white to pale green, sweet scented; pedicel 5.8‒8.4 mm long, 0.3‒0.7 mm diam.; sepals 3 or 4, ovate to elliptic, 2.5‒4 by 1‒2 mm, inside red; stamens 31–36, filaments c. 4 mm long, white, anthers c. 0.5 mm long, yellow. Pistillate flowers 0.9–2.3 mm diam., light green; pedicel c. 2.5 mm long, c. 0.8 mm diam.; sepals 5, triangular to ovate, 1.5‒3 by 0.5‒1.1 mm, inside red; ovary 2- or 3(4)-locular, ellipsoid, 1.7–2.3 mm high, 1.4–2.3 mm diam.; style indistinct, 0.3–0.5 mm long, stigma 1.3–4 mm long, recurved. Fruits ellipsoid to flattened-globular, 3.3–4.8 cm broad by 2.3–4.1 cm high, green to red-brown when dry; pedicel to 1 cm long, up to 3 mm diam., abscission zone basally; sepals not persistent; disc distinct; wall 4–7 mm thick, meso- and endocarp thickened, mesocarp sometimes with cavities when dry (see note 3), surface knobbly; margin mostly pitted when dry; endocarp enclosing 2 or more seeds; stigma usually long persistent. Seeds bean-shaped, 2–3.8 by 1.1–2.2 by 0.9–1.3 cm; sarcotesta yellow.

    T h a i l a n d.— Narathiwat (Kok Dan Peat Swamp Forest).

    D i s t r i b u t i o n.— Thailand, Malay Peninsula, Sumatra, Java, Borneo, Philippines, Sulawesi, Moluccas.

    E c o l o g y.— Primary dipterocarp lowland forest, peat swamp forest, mangrove, kerangas forest, riverine forest, secondary forests; soils: white sand, sandy clay, clay, sandstone. Altitude: sea level to 1400 m. Flowering and fruiting throughout the year.

    V e r n a c u l a r.— Ya ka (ยากา).

    U s e s.— Fruit is stated to be edible.