Malesian Euphorbiaceae Descriptions
Welzen, P.C. van & P.I. Forster. 2012. Five rare genera of Euphorbiaceae (sensu lato) in the Malay Archipelago: Alphandia, Ashtonia, Borneodendron, Cladogynos and Tapoïdes. Edeninburgh J. Bot. 69: 389–411.
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Cladogynos Zipp. ex Span., Linnaea 15 (1841) 349; Baill., Étude Euphorb. (1858) 468; Müll.Arg. in DC., Prodr. 15, 2 (1866) 895; Benth. in Benth. & Hook.f., Gen. Pl. 3 (1885) 323; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.vii (1914) 264; Ridl., Fl. Malay Pen. 3 (1924) 276; Gagnep. in Lecomte, Fl. Indo-Chine 5 (1926) 478; Backer & Bakh.f., Fl. Java 1 (1963) 485; Airy Shaw, Kew Bull. 26 (1972) 232; Whitmore, Tree Fl. Malaya 2 (1973) 78; Airy Shaw, Kew Bull., Addit. Ser. 4 (1975) 9, in key; G.L.Webster, Ann. Missouri Bot. Gard. 81 (1994) 79; Govaerts, Frodin & Radcl.-Sm., World Checkl. Bibliogr. Euphorb. 1 (2000) 341; Radcl.-Sm., Gen. Euphorbiacearum (2001) 182; Chayam. & Welzen, Fl. Thailand 8, 1 (2005) 158; Welzen, Edinburgh J. Bot. 69 (2012) 401; G.L.Webster in Kubitzki, Fam. Gen. Vasc. Pl. 11 (2014) 136. — Type: Cladogynos orientalis Zipp. ex Span.
Adenogynum Rchb.f. & Zoll., Acta Soc. Regiae Sci. Indo-Neêrl. 1 (1856) 23. — Chloradenia Baill., Étude Euphorb. (1858) 471. — Cephalocroton Hochst. sect. Chloradenia (Baill.) Müll.Arg., Linnaea 34 (1865) 155; in DC., Prodr. 15, 2 (1866) 760. — Conceveiba Aubl. sect. Adenogynum (Rchb.f. & Zoll.) Post & Kuntze, Lexicon (1904) 138. — Type: Adenogynum discolor Rchb.f. & Zoll. [= Cladogynos orientalis Zipp. ex Span.].
Shrubs (to treelets), monoecious. Indumentum densely tomentose (to sometimes somewhat floccose on stems), stellate (and simple hairs, latter longer than stellate hairs), present on most parts. Stipules late caducous. Leaves alternate, simple; petiole long, round to somewhat grooved above, slightly pulvinate at both ends, but less so basally; blade symmetric, papery, basally not to slightly peltate, margin (partly) coarsely dentate, teeth ending in small glands, lower surface usually whitish when dry, venation basally triplinerved, otherwise penninerved, nerves near margin connecting to veins ending in the glands in the teeth and connecting in the loops to veins interconnecting the nerves, third order veins scalariform, veinlets reticulate. Inflorescences axillary, usually bisexual with a short joined peduncle, splitting into 1 or 2 single pedicelled pistillate flowers and a pedicelled dense head with staminate flowers; bracts at the top of the peduncle often leaf-like, basally with 2 very small bracteoles, the latter with a big round gland basally at one side; bracts within staminate head minute. Flowers actinomorphic; petals absent. Staminate flowers (sub)sessile; calyx 4-partite, lobes valvate; disc absent; stamens 4, filaments free, glabrous, anthers subbasally dorsifixed, 2-thecate, opening latrorse with lengthwise slits, connective indistinct; pistillode slender, column short. Pistillate flowers pedicellate; sepals 5 or 6, usually foliaceous, glands alternating with sepals, perhaps disc-glands, round, similar to those next to bracteoles and stipules; ovary 3-locular, tomentose; ovules single per locule; style short, stigmas elongate, apically divided for c. 2/3 of the length, each lobe further divided but less deeply so, with short stigmatic papillae. Fruits capsular, lobed, tomentose, dehiscing into 2-valved cocci or 6 parts, wall hairy outside, thin, woody when dry; columella persistent, with 4 vein remnants apically per locule. Seeds ellipsoid-globose, marbled or not; caruncle small.
Distribution — A monotypic genus of tropical Southeast Asia and Malesia.
Cladogynos orientalis Zipp. ex Span.
Cladogynos orientalis Zipp. ex Span., Linnaea 15 (1841) 349; Müll.Arg. in DC., Prodr. 15, 2 (1866) 895; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.vii (1914) 265; Merr., Enum. Philipp. Fl. Pl. 2 (1923) 444; Ridl., Fl. Malay Penins. 3 (1924) 276; Gagnep. in Lecomte, Fl. Indo-Chine 5 (1926) 478; M.R.Hend., J. Malayan Branch Roy. Asiat. Soc. 17 (1939) 69; Backer & Bakh.f., Fl. Java 1 (1963) 486; Airy Shaw, Kew Bull. 26 (1972) 232; Whitmore, Tree Fl. Malaya 2 (1973) 78; Chayam. & Welzen, Fl. Thailand 8, 1 (2005) 158, plate VIII: 3; Chayam. & Welzen in Welzen & Chayam., Fl. Thailand 8, 2 (2007) 615, Fig. 6; Welzen, Edinburgh J. Bot. 69 (2012) 402, Fig. 5. — Cephalocroton orientalis (Zipp. ex Span.) Scheff., Ann. Mus. Bot. Lugduno-Batavi 4 (1868-69) 120. — Lectotype (Welzen 2012): Zippelius s.n. (L, designated here, barcode L 0164205), [Indonesia, Lesser Sunda Islands,] Timor .
Rottlera ? albicans auct. non Hassk.: Hassk., Cat. Hort. Bogor Alt. (1844) 238, only text. — Adenogynum discolor Rchb.f. & Zoll. in Zoll., Acta Soc. Regiae Sci. Indo-Neêrl. 1 (1856) 23; in Zoll., Linnaea 28 (1856) 325, see note 1. — Chloradenia discolor (Rchb.f. & Zoll.) Baill., Étud. Euphorb. (1858) 472; Craib, Aberdeen Univ. Stud. 57 (1912) 192. — Cephalocroton albicans (Hassk.) Müll.Arg., Linnaea 34 (1865) 155, nom. illeg. — Cephalocroton albicans (Hassk.) Müll.Arg. var. genuinus Müll.Arg., Linnaea 34: 155 (1865), nom. inval. — Cephalocroton discolor (Rchb.f. & Zoll.) Müll.Arg. in DC., Prodr. 15, 2 (1866) 761. — Cephalocroton discolor Müll.Arg. var. genuinus (Müll.Arg.) Müll.Arg. in DC., Prodr. 15, 2 (1866) 761, nom. inval. — Cladogynos orientalis Zipp. ex Span. var. genuina (Müll.Arg.) Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.vii (1914) 266, nom. inval. (see note 2). — Type: Zollinger 1550 (holo P, n.v.; iso HAL, L 2x), [Indonesia,] Java.
Adenogynum odontophyllum Miq., Fl. Ned. Ind. 1, 2 (1859) 400.— Type: Zollinger 1065 or Zollinger 1165 (holo U, U 0001873), [Indonesia, Sulawesi,] Salajer, at the coast.
Cephalocroton albicans Müll. var. virens Müll.Arg., Linnaea 34 (1865) 155. — Cephalocroton discolor Müll.Arg. var. virens (Müll.Arg.) Müll.Arg. in DC., Prodr. 15, 2 (1866) 761. — Cladogynos orientalis Zipp. ex Span. var. virens (Müll.Arg.) Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.vii (1914) 266. — Type: Guichenot s.n. (holo P), [Indonesia, Lesser Sunda Islands,] Timor.
Cladogynos orientalis Zipp. ex Span. var. grossedentata Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.vii (1914) 266, fig. 41. — [Baprea bicolor Pierre ex Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.vii (1914) 264, nom. nud., in synonymy]. — Type: Pierre 6213 (iso L, P), Cochinchina, Mt. Pra (Baprea bicolor Pierre on label, name published in synonymy by Pax & Hoffmann, 1914).
Adenochlaena siamensis Ridl., J. Straits Branch Roy. Asiat. Soc. 59: 180 (1911). — Type: Curtis 2112 (holo K), [Thailand,] Siam, Terutau.
Shrubs (to treelets), up to 5 m high, branches angled upwards, flowering branchlets 1.5–5 mm in diameter.; with ferrugineous indumentum when young. Stipules triangular (to slightly falcate), 0.7–3.8 by 0.7–0.8 mm, basally usually with a round gland, hairy outside, glabrous inside. Leaves: petioles 0.8–9 cm long; blade (ovate to) elliptic (to obovate), 4.2–21 by 2–11 cm, length/width ratio 1.6–2.6, base subpeltate or not, when so then for up to 4 mm, emarginate to rounded, margin usually (double) dentate, sometimes only subdentate in the upper half (to almost subentire), flat, apex acute to cuspidate, upper surface mid green to dull dark green, hairy when young, soon glabrescent with a few hairs left at the base of the midrib, lower surface white to greyish white, usually epidermis not visible except with specimens in Sulawesi and the Lesser Sunda Islands (see note 2), venation slightly sunken to slightly raised above, raised below, nerves 8 or 9 per side. Inflorescences usually greyish white; peduncle 0.5–2 cm long; bracts often with a glandular margin, either elliptic, up to 5.5 mm long or leaf-like and up to 9.5 by 3.3 mm, basal c. 3 mm petiole-like; bracteoles c. 0.5 by 0.3 mm. Flowers yellow-green to white. Staminate flowers in heads of 5–6.5 mm in diam.; flowers 1.5–2 mm in diameter; calyx 1.2–1.7 mm high, yellow, lobed in upper half to almost completely, lobes triangular to ovate, 0.7–1.7 by 0.7–1 mm, hairy outside in upper half, glabrous inside; filaments 2.1–3.2 mm long, anthers elliptic, 0.6–0.7 by 0.5–0.6 mm, yellow; pistillode 0.8–1 mm high. Pistillate flowers 7–8 mm in diam., pedicel up to 4 mm long in flower, up to 2.5 cm long in fruit; sepals recurved, greyish white, obovate (2.2–4.2 by 0.4–1.2 mm) to leaf-like (up to 9 by 2 mm), hairy outside, subglabrous inside, margin with glandular teeth, basal glands shortly stalked; ovary ovoid, c. 2 by 1.5–1.8 mm, hairy, style 1.1–1.7 mm long, hairy; stigmas 2.2–3.8 mm long, bright clear yellow, hairy underneath. Fruits 10–11 by 6–6.5 mm, whitish or greyish green; column 4–4.5 mm long. Seeds ellipsoid-globose, slightly flattened inside, 4–4.5 by 3–4 by 3.5–3.8 mm, wall marbled or not, raphe well visible; caruncle small, grooved.
Distribution — South China, Thailand, Indochina, Malesia: Malay Peninsula, Java, Philippines, Sulawesi, the Lesser Sunda Islands and the Moluccas.
Habitat & Ecology — Dry evergreen forest, secondary forest, gallery forest, Eucalyptus savannah, bamboo thickets, scrubby vegetation; common near streams and in open spots; soil often dry, half of specimens on limestone, other half on granite derived soils; altitude: 0–800(–1100) m. Flowering and fruiting whole year through.
Vernacular names — Lesser Sunda Islands, Flores: Mondjong keka; Komodo: Wajuh.
Notes — 1. Hasskarl (1844) incorrectly identified a specimen (Zollinger 1550) in the Bogor Botanical Garden (Indonesia, Java) with Blume’s description of Adisca albicans (= now Sumbaviopsis albicans (Blume) J.J.Sm.). Later, Zollinger (1856a, b) realised the specimen was of an undescribed species once Blume’s species flowered in Bogor and was found not to be the same. This means that Hasskarl’s entry in the Bogor catalogue has a confusing double meaning. Nomenclaturally, his name, Rottlera ? albicans, is a later homotypic synonym of Blume’s Adisca albicans (= Sumbaviopsis albicans (Blume) J.J.Sm.). However, the specimen Zollinger 1550 is an altogether different species later described by Zollinger (1856a, b) who, afraid of causing confusion with Blume’s species if he used albicans, instead used the epithet discolor. Therefore, later synonyms using the epithet albicans are illegitimate. Zollinger published the name twice in 1856, once in Dutch/Latin (1856a) and once in German/Latin (1856b). It is not clear which publication appeared first.
2. The use of the epithet var. genuina/us is invalid as it generally means that the taxon comprises the type of the species and then the autonym rule applies. However, here the epithet genuinus was first used by Müller (1865) under Cephalocroton albicans and later used by himself (1866) and Pax & Hoffmann (1914) for new combinations, all of which are also invalid. Pax & Hoffmann (1914) placed Cephalocroton albicans var. genuinus in the synonymy of Cladogynos orientalis and used the epithet in its original meaning as an infraspecific entity of Cladogynos orientalis, which, unlike what one expects based on the name, does not contain the type of the species.
3. There is some variation in the specimens. The dentation of the leaf blade margin is generally very obvious, but locally the leaves can be subentire, or only shortly dentate in the upper half. The leaves in specimens from the Philippines and on Sulawesi tend to be somewhat narrower and smaller than in W Malesia. In S Sulawesi and the Moluccas the leaf blades are broader than in W Malesia and the indument on the lower leaf surface can be far less dense with part of the lamina visible. Pax & Hoffmann (1914) used the degree to which the leaf blade base is peltate for their infraspecific classification. However, even within a single region the degree to which the leaf blade base is peltate varies from absent to present. Therefore infraspecific taxa are not maintained.