Malesian Euphorbiaceae Descriptions

40. DORYXYLON

 

P.C. van Welzen

 

Welzen, P.C.  van. 1999. Revision and Phylogeny of subtribes Chrozophorinae and Doryxylinae (Euphorbiaceae). Blumea 44: 411--436.

 

Phylogeny of Chrozophorinae s.l.

 

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Genus description

Species description

 

Doryxylon Zoll.

 

    Doryxylon Zoll., Natuurk. Tijdschr. Ned.-Indië 14 (1857) 172; Linnaea 29 (1859) 469; Merr., Sp. Blancoan. (1918) 221; Airy Shaw, Kew Bull. 37 (1982) 16; Alph. Enum. Euphorb. Philipp. Isl. (1983) 21; G.L.Webster, Ann. Missouri Bot. Gard. 81 (1994) 72; Welzen, Blumea 44 (1999) 423; Radcl.-Sm., Gen. Euph. (2001) 146. --- Type species: Doryxylon spinosum Zoll.

    Sumbavia Baill., Étude Euphorb. (1858) 390; Müll. Arg. in DC., Prodr. 15, 2 (1866) 727; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.vi (1912) 12. --- Type species: Sumbavia rottleroides Baill. [= Doryxylon spinosum Zoll.]

    [Mercadoa Naves in Blanco, Fl. Filip., ed. 3 (1877-83) t. 463, nom. nud. --- Based on Mercadoa mandalojonensis Naves = Doryxylon spinosum Zoll.]

 

(Shrub to) tree, probably monoecious, but usually only one sex per plant; flowering twigs smooth, very shortly tomentose when young, lenticellate, with a broad soft pith. Indumentum consisting of simple and stellate hairs. Stipules triangular, densely hairy outside except for the probably glandular apex, glabrous inside, early caducous, scars very indistinct. Leaves spirally arranged, simple; axillary bud often developed into a thorn, apex sharp to rounded; petiole relatively long, basally and apically pulvinate, with longitudinal grooves when dry, hairy; blade ovate, papery, symmetric, base peltate or not, emarginate to rounded, margin shallowly, bluntly dentate, teeth ending in glands, the latter basally more or less grouped and large in the non-peltate leaves, apex acute to acuminate, very apex round, upper surface glabrescent, bases of hairs showing as white dots, lower surface very densely hairy, without glands; venation palmate with secondary nerves ending open near margin, veins scalariform, quaternary veins reticulate. Inflorescences terminal racemes, single, seldom branching with very short branches, either staminate, pistillate or mixed with the basal flowers pistillate; rachis and pedicels somewhat longitudinally grooved when dry, densely hairy. Bracts linear, completely hairy. Flowers actinomorphic; pedicels with basal abscission zone. Staminate flowers: sepals 5, ovate to elliptic, valvate, outside densely hairy, inside glabrous; petals 5, elliptic, longer than sepals, membranous, glabrous, apex frayed, nerves many, parallel; stamens 110--130, free, on convex, stellately hairy receptacle, filaments thread-like, glabrous, anthers basidorsifixed, 2-locular, opening latrorse? with lengthwise slits; disc absent; pistillode absent. Pistillate flowers: sepals 5 or 6, ovate, imbricate?, densely hairy, inside mainly simple hairs; petals absent; disc annular, flat, glabrous; pistil 3- (or 4-)locular, one ovule per locule, smooth, tomentose; style short, hairy, stigmas entire, below hairy, above with long slender fimbriae. Fruits slightly lobed capsules, triangular in transverse section, septicidal from apex to base, loculicidal from base to apex, outside densely tomentose, inside glabrous except for a few hairs at the base, somewhat woody, thin-walled; column slender, apically not broadened to basally and apically broadened, hardly any remnants of the septa; septa with a single apical and basal vein. Seeds 3 per fruit, very angular and ribbed when immature; covered by a thin, fleshy sarcotesta. Embryo not seen.

    Distribution --- Monotypic, as the species.

 

Doryxylon spinosum Zoll.

 

    Doryxylon spinosum Zoll., Natuurk. Tijdschr. Ned.-Indië 14 (1857) 172; Linnaea 29 (1859) 469; Merr., Sp. Blancoan. (1918) 221; Enum. Philipp. fl. Pl. 2 (1923) 427; Airy Shaw, Kew Bull. 37 (1982) 16; Alph. Enum. Euphorb. Philipp. Isl. (1983) 21; Welzen, Blumea 44 (1999) 424, Fig. 3, Map 2. --- Sumbavia rottleroides Baill., Étude Euphorb. (1858) 390, nom. superfl.; Müll.Arg. in DC., Prodr. 15, 2 (1866) 728; Fern.-Vill., Nov. App. (1880) 193; Vidal y Soler, Phan. Cuming. Philipp. (1885) 143; Revis. Pl. Vasc. Filip. (1886) 243; Boerl., Handl. Fl. Ned. Ind. 3, 1 (1900) 285; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.vi (1912) 12, fig. 2: A--D; Merr., Fl. Manila (1912) 291. --- Type: Zollinger 3341 (P, holo; iso in L), Indonesia, Lesser Sunda Islands, Sumbawa, Bima.

    Adelia acidoton Blanco, Fl. Filip. (1837) 815, non L.; Fl. Filip., ed. 2 (1845) 562; Fl. Filip., ed. 3, 3 (1879) 226, t. 463. --- Neotype (proposed here): Merrill Species Blancoanae 933 (L, holo; iso in NY), Philippines, Luzon, Rizal Prov.

    [Mercadao mandalojonensis Naves in Blanco, Fl. Filip., ed. 3 (1877-83) t. 463, nom. nud.]

 

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(Small shrub to) tree, up to 15 m high, dbh up to 25 cm; flowering twigs 2--3 mm thick. Outer bark smooth to rough to sharply fissured, corky, (light) brown (to grey), c. 3 mm thick; inner bark (pale) brown to yellowish whitish or pale brown inside, fleshy, c. 1 cm thick; wood dirty white. Stipules 0.6--1.3 by 0.3--0.5 mm. Leaves: thorns up to 11 mm long; petiole 0.7--11 cm long; blade ovate, 2.8--12 by 2.2--12 cm, index 1--1.3, base up to 3(--7) mm peltate, dull dark green above, white to grey beneath, venation impressed above, raised below, nerves 5 or 6 per side. Inflorescences up to 10 cm long. Bracts 5.8--9.5 by 0.6--0.8 mm. Staminate flowers c. 14 mm in diam.; pedicel 3.2--3.8 mm long; sepals 5.8--7.5 by 2.2--3.5 mm; petals 6.2--8.3 by 2.7--3.5 mm, white; stamens: filaments c. 3.2 mm long, anthers c. 1.2 by 0.5 mm; receptacle c. 0.5 mm high. Pistillate flowers c. 7.5 mm in diam.; pedicel c. 4.2(--10.5 in fruit) mm long; sepals 4--6.7 by 1--2 mm; ovary ovoid, 3--6 by 3.5--5.5 mm wide; style 1--2 mm long, stigmas spreading, up to 2 mm long, apices recurved. Fruits 10--14 by 5--8 mm, brown; column c. 5.5 by 1 mm. Seeds 4--5 mm in diam.

    Distribution --- Malesia: disjunct in the Philippines (Luzon) and the Lesser Sunda Islands (Bali, Sumbawa, Flores).

 

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    Habitat & Ecology --- Commonly found in dry areas with a yearly dry monsoon: open places, savannah with trees, monsoon forest (with Schleichera, Schoutenia, Tectona, Protium, and Tamarindus), ridges; also along roads and near villages. Soil or bed rock: Calcareous, sand breccies, tuff. Altitude: sea level up to 275 m. Flowering: Apr.-- June (Philippines), June--Dec. (Lesser Sunda Islands); fruiting: May--July (Philippines), Dec.--May (Lesser Sunda Islands).

    Uses --- Noted to be of possible ornamental value.

    Vernacular names ---: Philippines: Aliparo, dilap, kilap, kirap (Tagalog); balintauak, malabuauan (Pampangan); kim-mo (Iloko) (Merrill, 1923). Lesser Sunda Islands, Flores: Bebang; Sumbawa: Kaju kali bemang, kaju wamba (Zollinger, 1857).

    Notes --- 1. The material only contained staminate flowers in bud or flowers which were just opening, therefore, a possible raised receptacle (torus) could not be observed. Also, only older pistillate flowers were present and no mature fruits.

2. The material from the Lesser Sunda Islands is only in minor details different from the Philippine specimens. Lesser Sunda Islands: leaves seldom peltate, glands along leaf margin larger, and basally (due to absence of peltation) often grouped as in the genus Melanolepis, the indumentum tends to be browner when dry, especially on the flowers.