Trigonostemon viridissimus (Kurz) Airy Shaw

Yu, R. - Y. & Welzen, P. C. van, 2020, A taxonomic revision of Trigonostemon (Euphorbiaceae) outside Malesia, Blumea 65 (1), pp. 25-52 : 44-45

30. Trigonostemon viridissimus (Kurz) Airy Shaw — sect. Tylosepalum

Trigonostemon viridissimus (Kurz) Airy Shaw (1971) 545; Whitmore (1973) 135; Airy Shaw (1975) 205;(1981) 358;(1982a) 36;(1983) 48; N.P.Balakr. & Chakrab.(1991) 631, f. 12; R.I. Milne (1995) 28,in key, 29, in key; R.Y.Yu & Welzen (2018) 221. — Sabia viridissima Kurz (1872) 304;Hook.f.(1876) 3; Kurz (1877a) 301. — Blachia viridissima (Kurz) King (1896) 455, in obs. — Kurziodendron viridissimum (Kurz) N.P.Balakr. (1966) 68, pl. 1, f. 1-7. — Lectotype (designated here): Kurz s.n. (K, barcode K000246872;iso K, barcode K000246871), India, Andamans.

Neotrigonostemon diversifolius Pax & K.Hoffm. (1928) 385; (1931) 169. — Type: Parker 2593 ( K), Myanmar, Mergui , Ngawun Reserve .

Trigonostemon chatterjii Deb & G.K.Deka (1965) 577; N.P.Balakr. (1983) 427. — Trigonostemon viridissimus (Kurz) Airy Shaw var. chatterjii (Deb & G.K.Deka) N.P.Balakr. & Chakrab. (1984c) 967, syn. nov.; (1991) 635; Talukdar et al. (2015) 10. — Type: Deka 19 (holo CAL (19A), barcode CAL0000023655 ; iso ASSAM * (19B–19E), India, Meghalaya, Jowai dist. , Dawki.

Trigonostemon viridissimus (Kurz) Airy Shaw var. confertifolius N.P.Balakr. & N.G.Nair (1982) 36,syn.nov.;N. P. Balakr. & Chakrab. (1991) 635. — Type: Balakrishnan & Nair 4773 (holo CAL (4773 A), not found; iso L (4773 B), not found, PBL (4773 C –4773 E), not seen), India, North Andamans , Saddle Peak .

Trigonostemon huangmosu Y.T. Chang (1983) 174; H. S. Kiu (1996) 167. — Type: Lüchun Exped. 1961 ( KUN, barcodes KUN1294366 , KUN1294367 ), China, Yunnan, Gejiu .

Shrubs or small trees, 1–10 m tall, stem up to 10 cm diam; flowering branches 1.5–3.2(–4.6) mm diam, pubescent when young, glabrescent. Indumentum of simple hairs; translucent (oil?) dots often present in green parts. Bark 0.1–0.3 mm thick, grey or pale to reddish brown or grey; wood pale yellowish, pith sometimes hollow. Stipules subulate to nipple-like, 0.4–1.5 mm long, caducous, often pubescent at base. Leaves: petiole terete but grooved above, 0.5–3.5(–5.5) cm long, 0.7–1.8 mm diam, wrinkled, pubescent when young; blade ovate to elliptic to oblong, sometimes (ob)ovate, (4.5–)8–24 by (1.5–) 2.5–9 cm, membranous to chartaceous, base acute or obtuse, often with 1–2 pairs of adaxial glands, margin entire or slightly distantly serrate, apex acuminate to caudate, upper surface glabrescent to glabrous, dark green, lower surface often sparsely pubescent, paler and dull green; venation triplinerved, midrib slightly raised above and elevated beneath, often pubescent, especially near base, secondary veins 5–10 pairs, bow-shaped and connected along margin, tertiary veins scalariform, veinlets reticulate. Inflorescences bisexual, terminal or axillary, loose panicles; main axis terete, up to 30 cm long, 0.4–2 mm diam, slightly pubescent; bracts lanceolate, 0.5–6 by 0.2–1 mm, pubescent. Staminate flowers 5–9 mm diam; buds conical; pedicel 4.5–9 mm long, 0.15–0.2 mm diam, glabrescent or slightly pubes- cent; sepals elliptic to orbicular to triangular, 1–1.7 by 0.6–1.2 mm, imbricate, margin somewhat undulate, apex rounded or truncate, sometimes with a short notch and an apical gland, pubescent outside; petals obovate, 3–6.5(–10) by 2.5–4.5(–7) mm, contort, membranous, with several distinct parallel veins, base cuneate or somewhat claw-like, entire, apex rounded, yellow to orange, glabrous; disc annular, margin undulate, reflexed, sometimes with 5 notches; stamens 3, androphore 0.7–1.5 mm long, free part of filaments 0.3–0.4(–0.6) mm long, anthers free, ellipsoid, 0.4–0.5 mm long. Pistillate flowers 5–9 mm diam; buds conical; pedicel slightly thickening toward apex, 0.3–1.4 cm long, apically 0.5–0.7 mm diam when flowering, elongating up to 1.1–2.9 cm long and 0.8–2 mm diam in fruit, glabrescent, often with translucent (oil?) dots; sepals, petals and disc as staminate flowers, petals caducous when fruiting; ovary 0.8–1.1 mm diam, glabrous, with numerous translucent (oil?) dots on surface, styles 0.2–0.7 mm long, stigmas 0.5–1.5 mm long, erect or bent, apically slightly thickened and slightly bifid or horseshoe-like. Fruits 1.1–1.5 cm diam, greenish, glabrous, smooth; sepals persistent but not accrescent; wall 0.4–0.5 mm thick, exocarp partly detaching; columella 5–6.3 mm long. Seeds 7–8 mm diam, with numerous translucent (oil?) dots on surface; hilum rhombic to oblong, 1.5 by 0.6–1.2 mm.

Distribution — India, Myanmar (Mergui), China, Laos, Thailand, Vietnam, Malay Peninsula, Sumatra, Java, Borneo, Philip- pines, Lesser Sunda Islands.

Habitat & Ecology — Primary to secondary forests, along coasts to hillsides, sometimes along rivers.

Note — The species has perhaps the widest distribution in the genus and displays a wide range of morphological variation, even within its type locality, the Andamans ( India). Because the variation appears to be continuous, it was not possible to distinguish between binomials; we thus treat them as a single species.

Key to the varieties

1. Inflorescences pendulous and often pubescent, axis sym- podial branching (at least at tertiary and lower branches); style distinct, up to 0.7 mm long; stigmas often erect................................... a. var. viridissimus

1. Inflorescences erect and glabrous, axis monopodial; style sometimes indistinct, 0.2–0.4 mm long; stigmas bent............................... b. var. elegantissimus