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Malesian Euphorbiaceae Descriptions |
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Welzen, P.C. van. 1995. Taxonomy and phylogeny of the Euphorbiaceae tribe Erismantheae G.L.Webster (Erismanthus, Moultonianthus, and Syndyophyllum). Blumea 40: 375–396.
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Moultonianthus Merr., Philipp. J. Sc. Bot. 11 (1916) 70; Pax in Engl. & Harms, Pflanzenfam., 2nd ed., 19c (1931) 158 (Erismanthus), 170; Steenis, Bull. Bot. Gard. Buitenzorg, ser. III, 17 (1948) 404; Airy Shaw, Kew Bull. 14 (1960) 394; Kew Bull. Add. Ser. 4 (1975) 176; Kew Bull. 36 (1981) 332; G.L.Webster, Ann. Missouri Bot. Gard. 81 (1994) 67; Welzen, Blumea 40 (1995) 384; Radcl.-Sm., Gen. Euphorbiacearum (2001) 123; G.L.Webster in Kubitzki, Fam. Gen. Vasc. Pl. 11 (2014) 107, Fig. 23. — Type: Moultonianthus borneensis Merr. (= Moultonianthus leembruggianus (Boerl. & Koord.) Steenis).
Tree or shrub, monoecious. Indumentum consisting of simple, hirsute to sericeous hairs, (seldom some stellately bundled ones present), very early glabrescent. Stipules large, interpetiolar, ovate, base cordate, long persistent. Axillary buds between leaves and stipules. Leaves simple, distichous, opposite; petiole not pulvinate; blade coriaceous, not punctate; base oblique, emarginate to shortly attenuate; margin (shallowly) serrate (to crenate), revolute, with a gland in each tooth; apex acuminate to cuspidate, very apex rounded; venation pinnate, looped and closed near the margin, indistinctly reticulate. Inflorescences axillary thyrses, flattened, with either staminate or pistillate flowers, together from one axillary meristem, alternating per node, subsericeous, glabrescent, purplish, brachyblasts either with short branches and many dichasial bundles of staminate flowers or with single pistillate flowers; staminate inflorescences caducous when pistillate ones fruiting. Bracts ovate to triangular, subsericeous outside. Pedicels purplish, apically broadened, with abscission zone. Flowers actinomorphic, scented, pistillate flowers opening after pollen release of staminate ones, petals longer than sepals. Sepals 5, imbricate, free, 3 smaller outside, ovate, subsericeous outside, margin ciliate, 2 larger inside, ovate to obovate, glabrous outside, margin with papillae; all basally thickened, margins membranous, inside glabrous, (reddish) yellow. Petals 5(–7), longer than the sepals, elliptic to obovate, imbricate, margin entire, apex rounded, glabrous, white. Disc-like lobes minute, 5, alternipetalous. Stamens 9–11 in staminate flowers, on short torus, free, in 2 whorls, either with short or long filaments; latter filiform, (sub)glabrous, white; anther elliptic, basifixed, opening latro-intrors with a slit, glabrous, chocolate brown; connective with an apical triangular appendix; 1 or 2 short staminodes in pistillate flowers. Pistil in pistillate flowers: ovary 3-locular, densely tomentose, light yellow; ovules one per locule, descending, epitropous, anatropous, attached halfway to column; style 1, short, hirsute; stigmas 3, white, divided almost up to the style, lobes flat, broad, above with dendritic papillae, on lower surface hirsute; in staminate flowers only 3 filiform stigmas, glabrous. Fruit a 3-lobed rhegma, subglobose, outside tomentose, glabrescent, inside glabrous, dehiscing septi- and loculicidally into 6 segments; wall thin, woody. Seeds 1–3 per fruit, brown, sometimes with light brown short longitudinal stripes, glossy, micropyle well visible; arilloid absent. Embryo not seen.
Distribution — Monotypic, only found in Malesia: Sumatra (only 1 specimen) and Borneo (Brunei, Kalimantan, Sabah, Sarawak).
Notes — 1. Airy Shaw (1960, 1975) discusses the opposite leaves with the interpetiolar stipules. He considers the stipules to be transformed leaves, which are decussate with normal leaves. The stipules are just below the normal leaves because of suspected sympodial growth. The sympodial growth is indeed present besides monopodial growth; often a terminal bud can be found among the leaves and stipules and an axillary bud has taken over the growth. However, we do consider the stipules to be real stipules, but not only one pair per leaf, but just one stipule per leaf. This reduction is accompanied by a horizontal displacement on the node, whereby the two stipules, one per opposite leaf, became interpetiolar. The displacement is also shown by the axillary buds, these are not any longer in the axil of the leaf, but they are found between leaf petiole and stipule.
2. Airy Shaw (1960) also describes an androphore for Moultonianthus and occasionally bisexual inflorescences (1975). The androphore is absent, but the receptacle is heightened into a torus. We did not find any bisexual inflorescences.
Moultonianthus leembruggianus (Boerl. & Koord.) Steenis, Bull. Bot. Gard. Buitenzorg, ser. III, 17 (1948) 405; Airy Shaw, Kew Bull. 14 (1960) 394; Kew Bull. Add. Ser. 4 (1975) 176; Kew Bull. 36 (1981) 333; Welzen, Blumea 40 (1995) 387, Fig. 3, Map 2. — Erismanthus leembruggianus Boerl. & Koord. in Koord.-Schum., Syst. Verz. II Abt. (1910) 30; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.vi (1912) 126; in Engl. & Harms, Pflanzenfam., 2nd ed., 19c (1931) 158. — Type: Koorders 22285 (BO, holo), Sumatra, bei Bivak am Seitenzweig des Bokko-Bokko Flusses (Mukomuko).
Moultonianthus borneensis Merr., Philipp. J. Sc. Bot. 11 (1916) 70; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.xiv (1919) 41; in Engl. & Harms, Pflanzenfam., 2nd ed., 19c (1931) 170. — Type: Native Collector 412 (PNH, holo, †; iso in L, UC), Borneo, Sarawak, near Kuching.
(Shrub to) tree, up to 22 m high, d.b.h. up to 40 cm, girth up to 0.75(–1.65) m; stilt roots and buttresses seldom recorded, latter up to 33 cm high, 5 cm thick; flowering branches 1.5–3 mm thick, smooth to slightly ribbed, glabrous (to hirsute, glabrescent). Outer bark grey-brown to red-brown when young, smooth to finely and shallowly boat-fissured, with rectangular flakes, 2–3 mm thick; inner bark yellow to red-brown. Sapwood white; heart wood yellowish. Leaves: stipules 0.8–4.5 by 0.5–3.6 cm, base broad, margin entire to subserrate, apex acute, (sub)glabrous; petiole 4–7 mm long, reniform in transverse section, above often sericeous; blade (ovate to) elliptic (to obovate), 5.5–26.5 by 2.5–11 cm, index 2.6–3.6, glabrous (to subsericeous mainly below), lighter green below, venation above in plain of leaf except for midrib, below raised, nerves 10–12 per side. Inflorescences up to 22 cm long. Bracts up to 1.3 by 1 mm. Staminate flowers 5–7 mm in diam.; pedicel 2.8–13.3 mm long, above abscission zone 1.8–11.3 mm long; sepals 1.4–3 by 1.5–2.8 mm; petals 5.3–7.5 by 1.8–2.3 mm; filaments: short ones 0.7–0.8 mm long, long ones 1.7–2 mm long, anthers 0.5–0.8 by 0.5–0.8 mm; appendix on connective up to 0.4 mm long; styles 3.5–5 mm long. Pistillate flowers c. 1 cm in diam.; pedicels 3–8.2 cm long, above abscission zone 1.9–5.3 cm long; sepals 2.5–5.5 by 2.9–5 mm; petals up to 15.5 by 6 mm; filament of staminodes: c. 0.5 mm long; anther c. 0.8 by 0.6 mm; ovary 2.8–4.2 by 2.5–5 mm, style c. 1 mm high; stigmas 3.5–4 mm long, lobes 2.5–3 mm long. Fruit 15-18 mm broad by 8–12 mm high, brown; wall c. 1 mm thick. Seeds ± globose, 9–10 by 8–10 mm; hilum 2–2.7 mm long. Embryo seen immature, at least 6 by 6 mm.
Distribution — Malesia: Sumatra (one specimen), Borneo (Brunei, Kalimantan, Sabah, and Sarawak), and the Philippines (Dinagat Isl. near Mindanao).
Habitat & Ecology — Mainly found in primary mixed lowland dipterocarp forest, but also in secondary and logged forests, often along rivers and on hills and ridges. Common in drier habitats. Soil: alluvial, sandy loam, clay-loam. Alt.: 10–670 m. Flowering: March to October; fruiting: March to November.
Vernacular names — Sabah: Ulas (Brunei); ulas bukit (Malay); ulas-ulas.
Note — Most specimens are glabrous, but some still have a sericeous or hirsute indumentum, partly because they are young, sterile shoots, which have not lost their hairs yet. The more pilose specimens are not geographically restricted (4 specimens spread over Borneo, one in Sumatra), therefore this character is not considered to be of taxonomic importance.
