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Malesian Euphorbiaceae Descriptions |
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Haegens, R.M.A.P. 2000. Taxonomy, Phylogeny, and Biogeography of Baccaurea, Distichirhops, and Nothobaccaurea (Euphorbiaceae). Blumea Suppl. 12: 1–216.
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Distichirhops Haegens, Blumea Suppl. 12 (2000) 193; Radcl.-Sm., Euphorbiacearum (2001) 63 (sub Baccaurea, should be Distichorrhops); G.L.Webster in Kubitzki, Fam. Gen. Vasc. Pl. 11 (2014) 85 (should Distichirrops). — Type: Distichirhops mitsemosik Haegens.
Shrub to tree, dioecious, Terminalia branching pattern absent. Indumentum of simple hairs. Bark finely fissured. Leaves simple, alternate, distichous; petiole apically pulvinate, transverse cracks often present; stipules triangular, caducous, ciliate; blade: base rounded to attenuate; margin entire, marginal glands present; apex acuminate to cuspidate; upper surface glabrous, sometimes densely hairy on veins, raised glands often present, sometimes granulate; lower surface sparsely to densely hairy, raised glands often present, discoid glands absent; nervation raised, secondary veins curved. Inflorescences axillary to cauline, reduced thyrses, solitary to few clustered together; flowers hypogynous, actinomorphic; pedicel with abscission zone. Staminate inflorescences unknown. Pistillate inflorescences not branched, 5–10-flowered; bracts inserted on rachis, 3 per flower, triangular. Pistillate flowers 1.5–2 mm diam.; sepals 4 or 5, caducous to persistent; petals absent; staminodes absent; disc absent; ovary cylindrical to globose, 2–4-locular, ovules 2 per locule, attached at apex of column, wings usually absent; stigmas not cleft to completely so; protuberances often present. Fruits 0–4-seeded berries to late dehiscing fleshy capsules; raised glands often present; arillode enclosing seed totally.
Distribution — Three species in Borneo and New Guinea.
Habitat & Ecology — Secondary forest. Soil: clay. Altitude: sea level up to 350(–1980 m). Flowering: June, August; fruiting: April, July, August, October.
Notes — 1. Distichirhops is a poorly known genus. It closely resembles Aporosa. However, as long as the staminate inflorescences of Distichirhops remain unknown, it is desirable to understand it as a distinct genus within the subtribe Scepinae. Distichirhops differs from Baccaurea, Nothobaccaurea, and Maesobotrya in the following characters: absence of the Terminalia branching pattern; distichous (not spiral) arrangement of the leaves. The main differences between Distichirhops and Aporosa are: three instead of one bract per pistillate flower; absence of the small pistillate disc present in Aporosa; presence of an abscission zone in the pedicel. Furthermore, all species have character combinations that are absent in Aporosa.
2. This genus is named for its distichous leaf arrangement and shrubby habit (the Greek word distichos = in two rows; the Greek word rhopo = shrub).
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1a. |
Leaves glabrous above. |
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1b. |
Leaves sparsely to densely hairy above. |
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Petioles very hairy. Leaf lamina elliptic to obovate, papery to slightly leathery, sparsely to densely hairy below. |
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2b. |
Petioles glabrous to subglabrous. Leaf lamina ovate, leathery, glabrous to subglabrous below. |
Distichirhops megale Haegens, Blumea Suppl. 12 (2000) 194, Fig. 3.28, Map 3. — Type: NGF (Streimann & Katik) 28659 (holo L), New Guinea, Milne Bay Prov., Junction Ugat and Mayu Rivers, near Mayu I.
Tree c. 10 m high, dbh c. 8 cm, branchlets velutinous. Leaves: petiole 4–12 mm long, velutinous, raised glands absent; stipules 2–3.5 by c. 1 mm, densely hairy outside, glabrous inside, not hyaline; lamina elliptic, 12–15.7 by 5.3–6.8 cm, l/w ratio 1.9–2.7, slightly leathery; base attenuate to cuneate; marginal glands present as small indentations; apex obtuse to cuspidate, (0–)14 mm long; upper surface sparsely hairy, velutinous at veins, small raised glands present, granulate, dull green when fresh, nervation not to slightly raised; lower surface glabrous, densely hairy on veins, discoid glands absent, green when fresh; secondary veins 7–10 per side, closed at margin; nervation reticulate to weakly scalariform. Staminate inflorescences unknown. Pistillate inflorescences cauline. Pistillate flowers: sepals caducous; ovary 3-locular. Fruits globose, 3-seeded, fleshy capsules, c. 40 by 40 by 40 mm, irregularly dehiscent, slightly ruminate when dry, raised glands present, sparsely hairy outside, glabrous inside; septa subglabrous, dark brown; pericarp 2.5–3 mm thick, inner layer up to 0.1 mm thick; column 34–38 mm long, straight, persistent; pedicel c. 20 mm long, slightly thickened at abscission zone, upper part 6–12 mm long. Seeds globose, laterally flattened, 25–30 by 13–29 by 5–10 mm; arillode yellow; cotyledons 12–13 by 16–17 by c. 0.1 mm; radicle 4–4.5 mm long; endosperm c. 1.5 mm.
Distribution — Papua New Guinea, Milne Bay Prov.
Habitat & Ecology — Altitude c. 350 m.
Notes — 1. The species is named for its big fruits (the Greek word megas = big).
2. Only known from the type specimen.
Distichirhops minor Haegens, Blumea Suppl. 12 (2000) 195, Map 3.45. — Type: SAN (Sigin et al.) 99863 (holo L; iso K), Malaysia, Sabah, Ulu sungei Padau Madau.
Tree 4–15 m high, dbh 2.5–10.2 cm, buttresses absent; branchlets subglabrous to densely hairy. Bark pale brown to grey when fresh, smooth; inner bark (pale) brown. Sapwood pale yellow to pale brown. Leaves: petiole 3.5–8(–11 in New Guinea) mm long, velutinous, transverse cracks present when old, dark to grey-brown when dry, blackish in New Guinea, raised glands rare; stipules triangular to lanceolate, 2–7.5 by 0.4–0.8 mm, sparsely to densely hairy outside, inside subglabrous, densely hairy at base; lamina obovate to elliptic, 6–13.5 by 1.5–4.5 cm, l/w ratio 2.3–3.8, papery to slightly leathery; base rounded to attenuate; apex acuminate to cuspidate, 4–25 mm long; upper surface glabrous, usually granulate, raised glands usually present; lower surface glabrous to sparsely hairy, velutinous on veins, discoid glands absent, raised glands usually present; grey to brown above, pale brown to green-brown below when dry; nervation whitish to grey to (dark) brown when dry; secondary veins 4–7 per side, looped and closed at margin (or ending open in New Guinea); nervation reticulate. Staminate inflorescences unknown. Pistillate inflorescences axillary to just below the leaves, solitary to 5 clustered together, 0.5–4.5 cm long, 0.5–1 mm thick, densely hairy to velutinous, 5–10-flowered, red; pedicel 1–3 mm long, abscission absent, densely hairy; bracts 3 per flower (1 large, 2 small), subglabrous to sparsely hairy outside, (sub)glabrous inside, margin ciliate. Pistillate flowers 1.5–2 mm diam.; sepals 4 or 5, ovate to triangular, 0.2–0.4 by 0.2–0.3 mm, subglabrous to sparsely hairy outside, (sub)glabrous inside, persistent; ovary globose to cylindrical, 1.5–2 by 1.3–1.7 mm, 2-locular, sparsely hairy (densely hairy at base); style absent; stigmas 0.4–0.5 mm long, cleft for upper 50–100%, persistent; lobes 0.3–0.4 by 0.3–0.4 mm, glabrous above, (sub)glabrous below, protuberances small, on both sides. Fruits globose to ellipsoid, laterally flattened, 0–2-seeded fleshy capsules, 9.6–10.5 by 5.5–7.4 by 4.5–8.5, dehiscing loculicidally, glabrous on both sides, subglabrous when young outside, raised glands absent; pericarp 0.6–1.3 mm thick; column 8–9 mm long, straight. Seeds ellipsoid, laterally flattened, c. 7 by 5.1 by 3.5 mm; cotyledons c. 5 by 0.5 by 0.1 mm.
Distribution — Borneo, Irian Jaya (Vogelkop).
Habitat & Ecology — Secondary forest. Altitude: 10–200 m. Flowering: June, August; fruiting: April, August, October.
Note — The species is named for the small size of the leaves and fruits.
Distichirhops mitsemosik Haegens, Blumea Suppl. 12 (2000) 196, Fig. 3.29, Map 3.46. — Type: LAE (Stevens) 55701 (holo L; iso LAE), New Guinea, Scarp of Tantam Plateau, overlooking Mayu River, Mt Suckling.
Shrub to tree 2–10 m high; branchlets glabrous. Bark grey-brown when fresh; inner bark red. Sapwood pale yellowish. Leaves: petiole 5–18 mm long, (sub)glabrous, transverse cracks present, raised glands present; stipules caducous; lamina ovate, 10.5–14 by 3.8–6.2 cm, l/w ratio 1.8–2.8, leathery; base attenuate; margin lowly undulated; apex acute, c. 7 mm long; upper surface glabrous, small raised glands present, not granulate, dull green when fresh, grey-green when dry, nervation not to slightly raised; lower surface (sub)glabrous, small raised glands present, discoid glands absent, shiny green when fresh, light brown when dry; secondary veins 5–7 per side, almost closed at margin; nervation reticulate. Staminate inflorescences unknown. Pistillate flowers: sepals persistent; ovary 3- or 4-locular; stigmas persistent. Fruits globose, 3- or 4-seeded berries, 31–33 by 33–35 by 33–35 mm, few raised glands present, glabrous outside and inside; septa subglabrous to sparsely hairy, yellowish; pericarp 9–13 mm thick, not dehiscent; column c. 19 mm long, straight; pedicel, upper part c. 2 mm long. Seeds ellipsoid, laterally flattened, c. 8 by 5.5 by 2.5 mm.
Distribution — Papua New Guinea: Milne Bay Prov.
Habitat & Ecology — Mixed montane forest. Altitude: c. 1980 m. Fruiting: July.
Vernacular names — Papua New Guinea: Mitsemosik (Hattam).
Note — The species is named for its vernacular name ‘Mitsemosik’ in the Hattam Language.
