Malesian Euphorbiaceae Descriptions

53. GYMNANTHES (Euphorbiaceae)

H.-J. Esser

Esser, H.-J. 1999. A partial revision of the Hippomaneae (Euphorbiaceae) in Malesia. Blumea 44: 149–215.

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Genus description

Key to the species

Species descriptions

Gymnanthes Sw.

    Gymnanthes Sw., Prodr. (1788) 95; Baill., Étude Euphorb. (1858) 530; Benth. in Benth. & Hook.f., Gen. Pl. 3 (1880) 255, 337; Pax in Engl. & Prantl, Nat. Pflanzenfam. 3, 5 (1890) 100; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.v (1912) 81; in Engl. & Harms, Nat. Pflanzenfam. ed. 2, 19c (1931) 191; G.L.Webster, J. Arnold Arbor. 48 (1967) 387; Taxon 32 (1983) 304; Ann. Missouri Bot. Gard. 81 (1994) 122 ; Esser, Blumea 44 (1999) 168; in Radcl.-Sm., Gen. Euphorbiacearum (2001) 382; G.L.Webster in Kubitzki, Fam. Gen. Vasc. Pl. 11 (2014) 195. — Excoecaria sect. Gymnanthes (Sw.) Griseb., Fl. Brit. W. Ind. (1859) 50. — Sapium sect. Gymnanthes (Sw.) T.Post & Kuntze, Lex. Gen. Phan. (1903) 498. — Lectotype (designated by Britton & Shafer, N. Amer. Trees, 1908: 600): Gymnanthes elliptica Sw.

    ?Ateramnus P.Browne, Hist. Jam. (1756) 339; Hallier, Meded. Rijksherb. Leiden 36 (1918) 4; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.xvii, add. VII (1924) 204; in Engl. & Harms, Nat. Pflanzenfam. ed. 2, 19c (1931) 207; Rothmaler, Feddes Repert. Spec. Nov. Regni Veg. 53 (1944) 5; G.L.Webster, Taxon 32 (1983) 304; Oe, Een revisie van Ateramnus (1988) 2; Kruijt & Zijlstra, Taxon 38 (1989) 322; G.L.Webster, Ann. Missouri Bot. Gard. 81 (1994) 122. — Lectotype (designated by Rothmaler, Feddes Repert. Spec. Nov. Regni Veg. 53, 1944: 5): Ateramnus lucidus (Sw.) Rothm., based on Gymnanthes lucida Sw; see note 2.

    Sarothrostachys Klotzsch, Arch. Naturgesch. 7 (1841) 185; Baill., Étude Euphorb. Atlas (1858) 13; L.C.Wheeler, Taxon 24 (1975) 537. — Stillingia sect. Sarothrostachys (Klotzsch) Baill., Étude Euphorb. (1858) 524; Adansonia 1 (1861) 351; Adansonia 6 (1867) 325. — Sebastiania sect. Gussonia (Spreng.) Müll.Arg. subsect. Sarothrostachys (Klotzsch) Müll.Arg. in DC., Prodr. 15, 2 (1866) 1175. — Sebastiania sect. Sarothrostachys (Klotzsch) Benth. in Benth. & Hook.f., Gen. Pl. 3 (1880) 336; Pax in Engl. & Prantl, Nat. Pflanzenfam. 3, 5 (1890) 94; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.v (1912) 118; in Engl. & Harms, Nat. Pflanzenfam. ed. 2, 19c (1931) 193. — Lectotype (designated by L.C.Wheeler, Taxon 24, 1975: 537): Sarothrostachys multiramea Klotzsch ex Wawra [= Gymnanthes multiramea (Klotzsch ex Wawra) Müll. Arg.].

    Duvigneaudia J.Léonard, Bull. Jard. Bot. État 29 (1959) 15; Kruijt & Roebers in Kruijt, Biblioth. Bot. 146 (1996) 12; G.L.Webster, Ann. Missouri Bot. Gard. 81 (1994) 123. — Type: Duvigneaudia inopinata (Prain) J.Léonard, based on Sebastiania inopinata Prain [= Gymnanthes inopinata (Prain) Esser].

Shrubs to trees. Monoecious. Flowering and fruiting twigs with leaves. Indumentum absent (rarely present in Neotropical species). Stipules broadly ovate-triangular, 0.5–2 mm long, undivided, glandless. Leaves regularly alternate; petiole short (up to 2 cm long), much shorter than blade, glandless; blade ovate to elliptic, 3–13 cm wide, base acute to subcordate, sometimes slightly attenuate, margin entire (serrate in some Neotropical species), apex acute to acuminate (rarely retuse in Neotropical species), glandless above, lower surface whitish-farinose or smooth and with a row of strictly marginal or submarginal glands, basal ones sometimes enlarged, secondary veins 10–16 pairs, arching and joined or not joined towards the margin, tertiary venation reticulate. Inflorescences terminal and axillary, yellowish, simple or compound, in the latter case several times branched only near base and giving the resemblance of crowded axillary thyrses, with short or no sterile basal region, pistillate and staminate flowers in same thryse but pistillate flowers often lacking, staminate thyrse 6–60 by 2–5 mm. Bracts of staminate cymules broadly triangular to elliptic, sometimes removed by a peduncle, glandless or with a pair of globose-cylindrical glands touching the axis of the thyrse or removed by a peduncle. Staminate cymules 1–3(–5)-flowered; bracteoles present. Staminate flowers with short to distinct (up to 2 mm long) pedicel, hardly elongating when flowering; calyx with usually 3 sepals, quite small and fused only at very base (larger and mostly fused in some Neotropical species; stamens 3 (up to 12 in some Neotropical species), filaments slightly longer than anthers. Pistillate flowers 1–3 at base of thyrse; pedicel distinct and often considerably elongating after fertilization to up to c. 20 cm length; calyx with 3 sepals, triangular, free to basally united, glandless; ovary 3-locular, sometimes with 3 pairs of appendages but never with rows of multiple appendages; style present, stigmata undivided, glandless. Fruit with distinct, often very long (up to 20 cm) pedicel; 3-seeded, smooth or with 3 pairs of appendages, dry and regularly opening along the septa (indehiscent and drupaceous in an African species); pericarp moderately thick (fruit length/pericarp thickness = c. 10/1), septa with a separate basal triangle and 1, sometimes divided, vascular strand each, remaining columella alate except at base. Seeds elliptic, dry, smooth, without caruncle (in some Neotropical species with a broadly conical caruncle).

    Distribution — Including Sarothrostachys and Duvigneaudia, Gymnanthes comprises c. 25 species. 21 of them occur in the New World from the USA (Florida) to the Antilles and Paraguay, two in Africa (Congo Basin from Camerun to Zaire), and two in Asia (endemic to Malesia).

    Notes — 1. Circumscriptions of Sarothrostachys (with compound thyrses) as well of Gymnanthes (with simple thyrses) in the sense of Pax & Hoffmann (1912), the latest available monograph, are still problematical and in need of revision. There is no doubt that the two Malesian species are closely related, but their generic affinity may have to be examined again when the Neotropical taxa are being revised.

2. Ateramnus, a poorly understood, Neotropical genus with very insufficient description and no known extant type, would have priority over Gymnanthes, if accepted as identical. However, the arguments given by Kruijt and Zijlstra (1989) are not convincing. In agreement with Webster (1994) I prefer a still doubtful position of Ateramnus instead of accepting a definite synonymy with Gymnanthes and changing the name of the latter. The neo-lectotype of Ateramnus proposed by Kruijt & Zijlstra, A. glandulosus (Sw.) C.D. Adams, is refused here; it is probably a species of Sebastiania, and the proposed choice was unnecessary.

Key to the species

1. Gymnanthes borneensis (Pax & K.Hoffm.) Esser

    Gymnanthes borneensis (Pax & K.Hoffm.) Esser, Blumea 44 (1999) 170, Map 3. — Sebastiania borneensis Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.v (1912) 122; Merr., Bibl. Enum. Bornean Pl. (1921) 347; Steenis, Bull. Bot. Garden Buitenz., Ser. 3, 17 (1948) 410; Airy Shaw, Kew Bull. 14 (1960) 396; Whitmore, Tree Fl. Malaya 2 (1973) 131; Airy Shaw, Hooker's Icon. Pl. 38 (1974) tab. 3723; Kew Bull. Add. Ser. 4 (1975) 195; Keßler & Sidiyasa, Tropenbos Ser. 7 (1994) 135, fig. 103; I.M.Turner, Gard. Bull. 47 (1995) 232; Esser, Blumea 44 (1999) 170. — Lectotype (Esser, 1999): Beccari PB 3127 (holo G; iso FI, n.v., K).

    Sebastiania lancifolia Steenis, Bull. Bot. Garden Buitenz., Ser. 3, 17 (1948) 410; Airy Shaw, Kew Bull. Add. Ser. 4 (1975) 195; Kew Bull. 36 (1981) 345. — Type: Bünnemeijer 6925 (holo BO, n.v.; iso K, L), Sumatra, Lingga Archipelago, P. Lingga, Sg. Tanda.

Shrub to small tree, up to 15 m high, girth up to 32 cm, with irregularly shaped stilt roots c. 50 cm long. Outer bark smooth, hooped, soft, pale yellowish to greyish-brown to dark green; inner bark hard, pale brown to creamish to orange-yellowish, 2.5 mm thick. Sapwood medium hard, whitish to yellowish to cream. Stipules not seen, scars c. 0.4 mm wide. Leaves: petiole (0.8–)1.2–2 cm long; blade ovate to elliptic, (10–)14–23 by (3–)5–13 cm, base acute to obtuse to rounded, often slightly attenuate, apex acute to acuminate, lower surface usually whitish-glaucous, rarely green and shiny, with 2–8 glands per side, 0.2–0.4 mm in diam. and 0.5–3 mm distant from margin, basal glands enlarged and 0.75–3 mm in diam. or rarely absent, secondary veins 10–16 pairs, angle with midrib 55–65(–75)°, arching and not or indistinctly joined. Inflorescences usually axillary and compound, entirely yellowish except for reddish bracts, with a sterile basal region up to 5 mm long, staminate part (6–)15–30 by 2–3 mm. Bracts of staminate cymules 0.4–1.2 by 0.4–0.8 mm, apex rounded to subacute, removed from the axis of the inflorescence by a peduncle 0.4–1 mm long, glandless. Staminate cymules 1-flowered. Staminate flowers: pedicel only up to 0.2 mm long; calyx 0.4–0.6 mm long; stamens with filaments 0.3–0.5 mm long when flowering, hardly present in bud, anthers c. 0.25 mm long. Pistillate flowers: pedicel nearly absent in bud, elongating to c. 10 mm length when flowering; calyx c. 0.8–1 mm long with free sepals; ovary smooth and without appendages; style 1–2 mm long, stigmata c. 3–4 mm long. Fruits pendant on pedicel (5–)8–17 cm long; schizocarp nearly circular to transversely elliptic in outline, 9–11(–13) by 13–19 mm, deeply sulcate, without appendages, reddish-pinkish; pericarp c. 1 mm thick. Seeds c. 6–6.5 by 5–6.5 mm, without caruncle, brown, sometimes spotted.

    Distribution — Malay Peninsula (incl. Singapore), Central Sumatra, Lingga Archipelago, Borneo (Sabah, Sarawak, Brunei, C Kalimantan).

(dots in Malaysia, South Sumatra, Borneo)

    Habitat & Ecology — Found in the understorey of primary mixed Dipterocarp forest or old secondary forest, also on ridges or hillsides or in semi-riverine, swampy, periodically flooded, and submontane heath forest. Soil: yellow and red clay, sand, serpentinite. Altitude 15–1,000 m. Flowering: February, March., June to November; fruiting: March to June, August to November.

    Vernacular names — W Kalimantan: Kelampah.

    Note — The lower leaf surface rarely lacks the whitish covering of waxes, but is shiny instead. At least in one case (Vermeulen 883) a specimen was found on ultrabasic (serpentinite) soil; in this case, the petioles are remarkably short (8 mm).

2. Gymnanthes remota (Steenis) Esser

    Gymnanthes remota (Steenis) Esser, Blumea 44 (1999) 172, Fig. 3, Map 3; H.Zhu, H.Wang & B.G.Li, Acta Phytotax. Sin. 38 (2000) 462. — Sebastiania remota Steenis, Bull. Bot. Garden Buitenz., ser. 3, 17 (1948) 410; Airy Shaw, Kew Bull. 36 (1981) 344. — Type: van Steenis 8273 (holo BO, n.v.; iso L), Sumatra, Atjeh Gajolanden, Poetjoek Anacin, see note.

Shrub to small tree, up to 6.5 m high. Stipules c. 0.5–1 by 0.75 mm. Leaves: petiole 0.4–0.9 cm long; blade elliptic, 8–12 by 3.5–4 cm, base obtuse, apex subacuminate, lower surface smooth and brighter but never whitish-glaucous and with (0–)4 glands per side, longitudinally elliptic, c. 0.7 by 0.2–0.3 mm and strictly marginal, basal glands not enlarged, secondary veins 10–15 pairs, angle with midrib 75–80°, arching and distinctly looped. Inflorescences usually axillary and rarely compound, without a sterile basal region, staminate part (10–)40–65 by 2–5 mm. Bracts of staminate cymules 0.6–1 by 0.5 mm, not removed from the axis, apex subacuminate, their glands 0.4–0.6 mm in diam. Staminate cymules 1-flowered. Staminate flowers: pedicel 1–1.7 mm long when flowering; calyx 0.5–0.75 mm long; stamens with filaments 0.5 mm long when flowering, hardly visible in bud, anthers 0.3–0.4 mm long. Pistillate flowers: pedicel elongating to 10–90 mm length; calyx with free sepals c. 0.5–0.7 mm long; ovary with 3 pairs of small appendages ("muricate"); style c. 0.5–1 mm long, stigmata 1–1.5 mm long. Fruits pendant on pedicel up to 9 cm long; schizocarp circular to transversely elliptic in outline, sulcate, mericarps 10–11 mm long; pericarp 1.2–1.5 mm thick. Seeds 0.7–0.75 by 0.55–0.65 mm, without caruncle, brown, spotted.

    Distribution — China (Yunnan), Cambodia, N Sumatra.

(squares in North Sumatra)

    Habitat & Ecology — Found in montane rainforest, also on limestone; locally common. Altitude 1,600–2,000 m. Flowering: January, March, August; fruiting: June, July.

    Note — The type cited by Van Steenis is van Steenis 8237. According to his collection list at L, this specimen indeed is Aneilema herbacea Wall. ex Kunth [currently accepted name: Murdannia japonica (Thunb.) Faden], a Commelinacea. Obviously, the digits have been confused, and the two sheets of van Steenis 8273 present at L, typical specimens of Gymnanthes remota, therefore are supposed to be isotypes of this species.