Malesian Euphorbiaceae Descriptions

16. BLACHIA (Euphorbiaceae)

P.C. van Welzen

van Welzen, P.C. 2015. A revision of the Malesian species of Blachia (Euphorbiaceae). Blumea 59: 163–166.

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Genus description

Key to the species

Species description

Blachia Baill.

    Blachia Baill., Étude Euphorb. (1858) 385, nom. cons.; Thwaites, Enum. Pl. Zeyl. 4 (1861) 277; Benth., J. Linn. Soc., Bot. 17 (1878) 226; in Benth. & Hook.f., Gen. Pl. 3 (1880) 301; Hook.f., Fl. Br. Ind. 5 (1887) 402; Trimen, Handb. Fl. Ceylon 4 (1898) 53; Brandis, Indian Trees (1906) 581; T.Cooke, Fl. Bombay 2 (1906) 602; Bourd., Forest Trees Travancore (1908) 339; Boerl., Handl. Fl. Ned. Ind. 3 (1909) 284; Talbot, Forest Fl. Bombay 2 (1911) 474; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.iii (1911) 36; C.E.Parkinson, Forest Fl. Andaman Isl. (1923) 236; Gamble, Fl. Madras (1925) 1337; Gagnep. in Lecomte, Fl. Indo-Chine 5 (1926) 410; Pax & K.Hoffm. in Engl. & Harms, Pflanzenfam. ed. 2, 19C (1931) 159; Airy Shaw, Kew Bull. 23 (1969) 121; Kew Bull. 26 (1972) 223; Whitmore, Tree Fl. Malaya 2 (1973) 68; Airy Shaw, Kew Bull., Add. Ser. 4 (1975) 57; Ramamoorthy in C.J.Saldanha & Nicolson, Fl. Hassan (1976) 332; Airy Shaw, Kew Bull. 37 (1982) 9; Alphabet. Enum. Euphorb. Philipp. Isl. (1983) 10; N.P.Balakr. & Chakrab., Proc. Indian Acad. Sci., Pl. Sci. 99 (1989) 568; Thin, J. Biol. (Vietnam) 11 (1989) 16; G.L.Webster, Ann. Missouri Bot. Gard. 81 (1994) 107; Philcox in Dassan., Rev. Handb. Fl. Ceylon 11 (1997) 105; Radcl.-Sm., Gen. Euphorbiacearum (2001) 304; Phattar. & Chayam. in Chayam. & Welzen, Fl. Thailand 8, 1 (2005) 126; Thin, Taxon. Euphorb. Vietnam (2007) 260; G.L.Webster in Kubitzki, Fam. Gen. Vasc. Pl. 11 (2014) 176; Welzen, Blumea 59 (2015) 163. — Codiaeum A.Juss. sect. Blachia (Baill.) Müll.Arg. in DC., Prodr. 15, 2 (1866) 1118. — Type: Blachia umbellata (Willd.) Baill.

    Bruxalnelia Dennst. ex Kostel., Allg. Med.-Pharm. Fl. 5 (1836) 2002, nom. rej. — Type: Bruxanelia indica Dennst. ex Kostel.

Shrubs to shrubby trees, mainly monoecious; without latex. Indumentum simple hairs, sericeous or hirsute, often most parts glabrescent. Stipules absent, but axillary bud scales at base of sidebranches and inflorescences resemble stipules; latter ovate, glabrous (to hairy), late caducous. Leaves spiral, simple, glandless; petiole short, not pulvinate; blade sometimes with basal 4 or more papillate- or 2 stipule-like stipellae, then these often obscured by hairs; base usually slightly oblique, with an (sub)entire margin, penninerved. Inflorescences terminal (or terminal on short axillary branches), racemes with per node subumbellate groups of flowers; bisexual with staminate flowers above and pistillate flowers below or unisexual; bracts absent, though usually new leaves developing at lower nodes. Staminate flowers pedicellate, with abscission zone in lower third or halfway; sepals (4)5(6), basally connected, imbricate, membranous, margin entire; petals (4)5(6), free, shorter than sepals, membranous; disc glands (4)5(6); stamens 14–24, filaments free (to adnate when young, also to disc), flat, tapering towards apex, anthers basifixed, 2-thecate, opening latrorsely with longitudinal slits; pistillode absent. Pistillate flowers pedicellate; sepals 4–6, triangular, persistent, often accrescent in fruit (not in Thailand); petals often absent, sometimes 1—5 present; disc lobes 5 or 6, often appearing as lobed ring; ovary (2)3-locular, ovules single per locule; stigmas free, bifid. Fruits capsules, lobed or rather globose; septicidally dehiscent into 2-valved cocci; septa thickened above attachment of seeds; columella persistent. Seeds brown; ecarunculate to carunculate.

    Distribution — Twelve species in tropical asia from India to China (Hainan) to the Malay Peninsula and the Andaman Island, also one species in the Philippines. Two species in Malesia (Malay Peninsula and Philippines, respectively). 

    Classification — Subfam. Crotonoideae, tribe Codiaeae.

Key to the species

1. Blachia andamanica (Kurz) Hook.f.

   Blachia andamanica (Kurz) Hook.f., Fl. Brit. Ind. 5 (1887) 403; Brandis, Indian Trees (1906) 581; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.iii (1911) 38; Merr., J. Straits Branch Roy. Asiat. Soc., special number (1921) 346; Gagnep. in Lecomte, Fl. Indo-Chine 5 (1926) 416; Airy Shaw, Kew Bull. 23 (1969) 121; Kew Bull. 26 (1972) 223; Whitmore, Tree Fl. Malaya 2 (1973) 68; Airy Shaw, Kew Bull. 37 (1982) 9; Phattar. & Chayam. in Chayam. & Welzen, Fl. Thailand 8, 1 (2005) 127, fig. 27, plate VII: 1; Welzen, Blumea 59 (2015) 164, fig 1h. — Codiaeum andamanicum Kurz, Forest Fl. Burma 2 (1877) 405. — Type: Not indicated.

Shrubs to shrubby trees, up to 6 m high, basal diameter up to 6 cm; branches arching, (dark) brown; flowering ones 1.3–3 mm thick; young parts often sparsely hairy. Outer bark thin, smooth to very finley cracked, light green to grey. Axillary bud scales 3–4.8 mm long, glabrous. Leaves: petiole 5–9.5 mm long, not pulvinate, glabrous to few hairs, seldom with transverse corky cracks, above sharply V-shaped in transverse section; blade ovate to elliptic to oblong to obovate, often various shapes present per specimen, (3.1–)7.8–17 by (1.8–)3–10 cm, length/width index 1.7–3.3, papyraceous to subcoriaceous, symmetric except base, base cuneate or rounded, usually slightly oblique, margin entire, usually somewhat reflexed, apex acuminate to cuspidate, subglabrous when young, glabrescent, upper surface mid green to glossy dark green, lower surface slightly paler than above to light green; venation slightly raised on both sides, nerves 6–12 pairs, looped and closed near the margin, intercalary veins distinct, veins reticulate. Inflorescences terminal (to axillary), up to 8 cm long, light green, with few hairs; buds light green. Staminate flowers 4.8–5.2 mm in diameter; pedicel 5–9 mm long; sepals (4)5(6), elliptic to obovate, 2–3.5 by 2–3 mm, pale green (to white), apex rounded; petals (4)5(6), obtriangular, 0.7–1.8 by 0.8–2 mm, glabrous, membranous, apex erose to c. 3-lobed, white to light yellow; disc glands (4)5(6), obtrapezoid, 0.7–1.2 by 1.2–1.6 mm, thick, glabrous, apex 3-lobed; stamens 20–24, filaments 1.2–3 mm long, very pale light greenish, anthers elliptic or thecae separated by triangular connective, 0.6–0.7 by 0.3–0.6 mm, light yellowish. Pistillate flowers 2–4 mm in diameter; pedicel 2–5 mm long; sepals 5, ovate (to triangular), 1–2 by 0.8–1.3 mm, variably in size per flower, light green, ridged abaxially or not, glabrous to few hairs to hairs along margin; disc 5-lobed; ovary 3-locular, subovoid, 3-lobed, 1.2–1.5 mm high by 1.1–1.8 mm wide, green, densely sericeous; style short, 0.4–0.8 mm long, basally hairy, light green, stigmas 3–5.2 mm long, split except for basal 0.6–1 mm, light green. Fruits on elongated pedicel, up to 10 mm long, obovoid, 3-lobed, 13–14 by c. 11 m high, young fruit somewhat winged on lobes, green to purplish tinged, few hairs, glabrescent; sepals slightly accrescent to 2.8 by 1.3 mm; style and stigmas persistent; columella c. 6 mm long. Seeds ± oblong, but somewhat triangular in transverse section, c. 7 by 6.2 by 6 mm, slightly marbled, caruncle present or absent.

    Distribution —Thailand, Andamans and perhaps the Malay Peninsula. Phattarahirankanok & Chayam. (2005) report this species also for Assam, Myanmar, Borneo, Philippines, Sulawesi (Celebes), Moluccas, and the Lesser Sunda Islands. I have not seen any Blachia specimens from these areas except for Assam, there a different species is present.

    Habitat & Ecology — Dry evergreen forest, mixed evergreen and deciduous forest, secondary forest, usually by streams; on limestone and quartzite or granite bedrock. Altitude: sea level up to 600 m. Flowering: January to March, July, August, November; fruiting: January, February, November.

2. Blachia philippinensis Merr.

   Blachia philippinensis Merr., Philipp. J. Sci. 4, Bot. (1909) 277; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.v (1911) 285; Merr., Enum. Philipp. Fl. Pl. 2 (1923) 455; Welzen, Blumea 59 (2015) 164, fig. 1a–g. — Lectotype (van Welzen, 2015): Curran FB 4128 (holo L), Philippines, Palawan, near Puerto Princesa. (Syntypes: Curran & Merritt FB 8369, Philippines, Luzon, Pangasinan Prov.; Merritt & Darling FB 13829, Philippines, Luzon, Ilocos Norte Prov., Cape Bojeador.).

    Blachia andamanica auct. non (Kurz) Hook.f.: Airy Shaw, Alphabet. Enum. Euphorb. Philipp. Isl. (1983) 10.

Shrubs to shrubby trees, up to 5 m high, dbh 2 cm or more; flowering branches 1–2 mm thick; young parts with very few hairs. Axillary bud scales 2.3–3.5 mm long, glabrous. Leaves: petiole 5–12 mm long, not pulvinate, green, often (especially older ones) with transverse corky cracks, then brownish green, glabrous to few hairs when young, above sharply V-shaped in transverse section; blade ovate to elliptic, 4.1–9(–14.5) by 1.1–3.5(–5) cm, length/width index 2.4–4(–5.4), subcoriaceous, symmetric to asymmetric, base cuneate, margin entire, wavy, usually somewhat reflexed, apex(acute to) cuspidate to caudate, subglabrous when young, glabrescent, upper surface glossy dark green, lower surface pale green to dull green; venation slightly raised on both sides, midrib especially raised beneath, nerves 8–12 pairs, looped and closed near the margin, intercalary veins distinct, veins reticulate. Inflorescences terminal (to axillary), up to 3 cm long, with few hairs; buds green. Staminate flowers c. 3.5 mm in diameter; pedicel 7–7.5 mm long; sepals 5, elliptic, c. 2.3 by 1.5 mm, white, apex rounded; petals 5, obovate, c. 0.9 by 0.6 mm, glabrous, membranous, apex slightly emarginate; disc glands 5, obtrapezoid, c. 0.9 by 0.8 mm, thick, glabrous, apex slightly 3-lobed; stamens c. 20, filaments c. 2 mm long. slender, slightly thickened basally, anthers elliptic, c. 0.4 by 0.4 mm. Pistillate flowers c. 2.5 mm in diameter; pedicel 3–4 mm long; sepals 5, triangular, 1.5–2.5 by 0.6–0.8 mm; petals 1–5, in young flower hardly visible, clear in fruit, triangular to ovate, c. 0.7 by 0.3–0.4 mm; disc lobes 5 when young; ovary 3-locular, ovoid, 3-lobed, c. 0.8 mm high by 0.8 mm wide, somewhat hairy in lower half; style short, 0.5–0.8 mm long, glabrous, stigmas 1.7–2.8 mm long, split except for basal 0.4–0.8 mm. Fruits on elongated pedicel, up to 10 mm long, obovoid, 3-lobed, c. 10 by 10 mm high, green when young, glabrous; sepals, petals, style and stigmas persistent, not enlarging; columella 6–7 mm long, apically not enlarged and T-shaped. Seeds ± oblong, but somewhat triangular in transverse section, c. 8 by 5.5 by 5 mm, slightly marbled, caruncle present.

    Distribution — Philippines (Palawan).

    Habitat & Ecology — Along edge of forest, lowland mixed forest along river, soil clay. Altitude: 300–450 m. Flowering: February to April; fruiting: February, August.

    Vernacular name — Pañgapien (Ilk.; Merrill, 1923).