Malesian Euphorbiaceae Descriptions

11. AUSTROBUXUS (Picrodendraceae)

 

P.C. van Welzen & P.I.Forster

 

Welzen, P.C. van & P.I. Forster. 2010. A revision of Malesion Austrobuxus (Picrodendraceae / Euphorbiaceae s.l. subfam. Oldfieldioideae). Nordic J. Bot. 28: 189–195.

van Welzen, P.C. & Forster, P.I. 2011. Picrodendraceae (formerly Euphorbiaceae s.l. subfam. Oldfieldioideae). In: Nooteboom, H.N. (ed.), Flora Malesiana ser. 1, 20: 45–61.

 

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Genus description

Key to the species

Species descriptions

 

Austrobuxus Miq.

 

    Austrobuxus Miq., Fl. Ned. Ind., Eerste Bijv. (1861) 444; Mόll.Arg. in A.DC., Prodr. 15, 2 (1866) 1254; Steenis, Blumea 12 (1964) 362; Airy Shaw, Kew Bull. 25 (1971) 506; Whitmore, Tree Fl. Malaya 2 (1973) 63; Airy Shaw, Kew Bull. 29 (1974) 303; Kew Bull. Add. Ser. 4 (1975) 43; Kew Bull. 35 (1980) 597; Kew Bull. 36 (1981) 258; McPherson & Tirel, Fl. Nouv.-Calιd. 14 (1987) 187; G.L.Webster, Ann. Missouri Bot. Gard. 81 (1994) 57; P.I.Forst., Austrobaileya 4 (1997) 620; Radcl.-Sm., Gen. Euphorbiacearum (2001) 90; S.S.Larsen in Chayam. & Welzen, Fl. Thailand 8 (2005) 105; Welzen & P.I.Forst., Nordic J. Bot. 28 (2010) 189; in Noot., Fl. Males. ser. 1, 20 (2011) 48; G.L.Webster in Kubitzki, Fam. Gen. Vasc. Pl. 11 (2014). — Type: Austrobuxus nitidus Miq.

    Buraeavia Baill., Adansonia 11 (1873) 83; Guillaumin, Fl. Anal. Synopt. Nouv.-Calιd. (1948) 181. — Lectotype (designated by Webster, 1994): Buraeavia carunculata (Baill.) Baill. [= Austrobuxus carunculatus (Baill.) Airy Shaw].

    Choriophyllum Benth., Hooker’s Icon. Pl. 13 (1879) 62, t. 1280. — Type: Choriophyllum malayanum Benth. (= Austrobuxus nitidus Miq.).

    Longetia auct. non Baill. ex Mόll.Arg.: Ridl., Fl. Malay Penins. 3 (1924) 224; Corner, Ways. Trees Malaya 1 (1940) 260.

 

Shrubs to trees, dioecious; latex absent. Indument of simple hairs, most parts glabrescent; glandular and stinging hairs absent. Stipules absent (Malesia). Leaves simple, decussate; axillary buds usually covered by two relatively big bracts, easily mistaken for stipules; petiole channelled above; blade symmetric, coriaceous, base attenuate to cuneate, margin entire to very laxly crenulate, flat to recurved, with very small glandular dots or teeth in shallow cavities, drying blackish; venation pinnate, generally indistinct, nerves looped and closed near margin, veins reticulate. Inflorescences axillary, imperfectly cymose, often thyrsoid, staminate ones with several flowers per node, pistillate ones generally single or in small groups; bracts hairy outside, glabrous to slightly hairy inside. Flowers actinomorphic; pedicel slightly hairy, glabrescent; sepals imbricate, glabrous to slightly hairy outside; petals absent. Staminate flowers pale green to yellowish to white, fragrant; pedicel round; sepals free, reflexed, the 2 outer ones smaller; stamens 4–9 (Malesia), around a raised receptacle, filaments glabrous; anthers elliptic, basi-dorsifixed, opening latero-extrorsely with longitudinal slits; pistillode absent, but receptacle raised and pistillode-like. Pistillate flowers: pedicel often elongating in fruit; sepals 4–8, ovate, tightly together in the young flower, apex rounded, outer ones very thick (and if present, inner ones thinner, with membranous upper margin); ovary 2–4-locular, 2 ovules per locule; style absent, stigmas short, reniform to completely split, shortly papillate above. Fruits rhegmas, red, exo- and mesocarp detaching, endocarp woody, dehiscing into 2-valved cocci from base to apex, completely loculicidal, partly septicidal; persistent column very slender, basally with collar of carpel remnants, apically shortly T-shaped. Seeds obovoid, at most one developing per locule, other abortive, shiny, caruncle yellowish to black when dry, orange to deep red when fresh, consisting of short to longer papillae.

    Distribution — About 25 species, the majority endemic in New Caledonia, the rest in Australia and the West Pacific, three species in Malesia.

    Note — Austrobuxus was synonymized for a long time with Longetia Baill. ex Mόll.Arg. (the name Longetia is younger than Austrobuxus, but it was generally used as accepted name). McPherson & Tirel (1987) redefined the generic circumscriptions, both are separated based on different pollen types. Longetia is presently a monotypic genus of New Caledonia, while Austrobuxus is the species richest genus within the Picrodendraceae with also its main centre of distribution in New Caledonia.

 

Key to the species

 

 

1a.

Leaf blade margins with black glandular dots, no teeth — Thailand, W Malesia, Sulawesi

2

1b.

Leaf blade margins with black drying glandular teeth (check several leaves, teeth caducous, leaving glandular dot-like scars) — New Guinea

2. Austrobuxus dentatus

2a.

Caruncle with up to 5 mm long, wavy papillae. Ovary 2-locular. Fruits 9–12 by 8–9 mm. Leaves up to 8 cm long. Staminate flowers with 4 sepals and 4 stamens. — Sulawesi

1. Austrobuxus celebicus

2b.

Caruncle with up to 1.5 mm long, straight papillae. Ovary 2–4-locular. Fruits 10–22 by 9–16 mm. Leaves up to 16 cm long. Staminate flowers with (3)4 or 5 sepals and (4)5 stamens. — Thailand, W Malesia

3. Austrobuxus nitidus

 

1. Austrobuxus celebicus Welzen & P.I.Forst.

 

    Austrobuxus celebicus Welzen & P.I.Forst., Nordic J. Bot. 28 (2010) 190, Fig. 1a–c, 3; in Noot., Fl. Males. ser. 1, 20 (2011) 48, fig. 1a–c; Map 1. — Type: E.F. de Vogel 6392 (L holo; iso L), Celebes, Sulawesi Selatan, north shore of Lake Towuti.

 

   

 

(Shrubs to) trees, up to 13 m high, dbh up to 30 cm; branchlets usually lenticellate when older, flattened when young, diameter of flowering ones 1.5–3 mm. Indument of brownish hairs. Outer bark nearly smooth to cracking and fissured vertically to flaky, brown to brownish grey to purplish grey; inner bark dark brown. Leaves: petiole 5–8 mm long, slightly hairy when young; blade elliptic (to somewhat obovate), 2.5–8 by 1–3.2 cm, length/width ratio 2.3–3.2, margin flat (to slightly recurved), with glandular dots, apex bluntly acute to acuminate, upper surface basally very slightly hairy when young, smooth, lower surface hairy when young, soon glabrous, smooth; venation indistinct, nerves 8–10 per side. Inflorescences single, basally cymose to upward imperfectly cymose, sericeous, staminate ones up to 2.4 cm long; bracts triangular, largest ones c. 2.1 by 1.2 mm wide. Staminate flowers c. 2.5 mm in diameter, buds greenish yellow; pedicel 3–3.8 mm long; sepals 4, ovate, 2 outer 1–1.2 by 1–1.2 mm, 2 inner 1-3–1.5 by c. 1.3 mm; stamens 4, filaments c. 1 mm long, anthers c. 0.7 by 0.6 mm, pale to golden yellow; receptacle somewhat hairy. Pistillate flowers not seen, data from fruits; pedicel 3–4 mm long; outer sepals 4(5?), ovate, c. 1 long by 1.2 mm wide, thick; ovary 2-locular; stigmas split, lobes up to 0.6 mm long, shortly papillate above. Fruits ellipsoid, 9–12 mm high by 8–9 mm wide, wall thin, up to 1 mm thick; column7–9 mm long. Seeds 5.5–6 by c. 3 by 1.5–2 mm, shiny dark brown when dry, caruncle black when dry, consisting of long, wavy papillae in a loose group, up to 5 mm long.

    Distribution — Endemic on Sulawesi.

« = A. celebicus; = A. dentatus; l = A. nitidus

    Habitat & Ecology — Grasslands with short forest, heath forest; soil sandy, generally iron rich ultrabasic/serpentine. Altitude: 300–1700 m. Flowering: June to July; fruiting: July, August.

    Note — Very likely an endemic species of ultrabasic soils.

 

2. Austrobuxus dentatus Welzen & P.I.Forst.

 

    Austrobuxus dentatus Welzen & P.I.Forst., Nordic J. Bot. 28 (2010) 190, Fig. 1d–e, 3; in Noot., Fl. Males. ser. 1, 20 (2011) 51, fig. 1d–e; Map 1. — Type: Versteegh BW 266 (holo L; iso L), Netherlands New Guinea [= Indonesian Papua], Arfak Mountains, Anggi Lakes, Lake Anggi Gigi, Iray.

 

   

 

Shrubs to trees, up to 12 m high, dbh up to 15 cm; flowering branchlets 2–4.5 mm diameter, somewhat wrinkled when dry, the youngest shoots somewhat flattened, smooth, the older ones rough. Outer bark cracked with reticulate grooves, brown; wood quite tough, without exudate nor smell; sapwood pink; heartwood pale straw-coloured. Leaves: petiole 3–8 mm long, slightly hairy when young, red; blade elliptic to obovate, 2.5–10 by 1–4.7 cm, length/width ratio 1.7–3.6, margin recurved, with teeth, these drying black, caducous, scar glandular dot-like, apex rounded to blunt, upper surface glabrous, smooth, dark green, lower surface slightly hairy when young, soon glabrous, smooth, light green; venation distinct on both sides especially the lower surface, nerves 8–11 per side. Staminate inflorescences and flowers unknown. Pistillate inflorescences single to few together, cymose, somewhat hairy, up to 1.7 cm long; largest bracts triangular, c. 1.5 by 1.5 mm, slightly hairy outside. Pistillate flowers unknown, data from fruits; pedicels up to 10 mm in fruit, slightly hairy; sepals 4, ovate, c. 1.6 high by 2 mm wide, outside and especially the margin hairy; disc entire to lobed, hairy; ovary 2–4-locular, glabrous?; stigmas reniform when young to soon completely split. Fruits subglobose, 14–15 high by 13–14 mm wide, yellow to (orange-)red to brownish red, glossy, wall generally thin, up to 1 mm thick; column 11–13 mm long. Seeds obovoid, c. 7 by 4.8 by 3 mm, red, shiny light brown when dry; caruncle yellow, black when dry, consisting of straight, middle-long to long papillae, up to 2–5 mm long, drying yellowish (long) to brownish to blackish (short), in a rather loose group.

    Distribution — Endemic in New Guinea (Indonesian Papua).

« = A. celebicus; = A. dentatus; l = A. nitidus

    Habitat & Ecology — Mixed heath forest, scrubby woodland with open places, primary forest, young secondary forest; soil: peaty clay, with limestone and sandstone boulders and outcrops. Altitude: 580–2100 m. Fruiting: February, April–June, August.

    Vernacular names — Meptekeh (Dani); Seroema (Manikiong); Taoewa (Kapaukoe).

    Note — This species is only found at higher altitudes, the most western specimen (Map 1) was collected at the lowest altitude, all others are above 1700 m. Typical are the black drying, glandular teeth along the leaf blade margins, which are caducous and leave as scar a black dot similar to the glandular dots found in all other species and perhaps with still a glandular function. There is some variability. The two most eastern localities (Map 1) tend to have larger leaves and caruncle papillae that are up to 5 mm long and which dry yellowish; while the two central specimens have very small leaves, and much shorter papillae (2 mm) that dry black. The most western specimen is in between in leaf size, has > 2 mm long papillae, which dry brownish.

 

3. Austrobuxus nitidus Miq.

 

    Austrobuxus nitidus Miq., Fl. Ned. Ind., Eerste Bijv. (1861) 445; Airy Shaw, Kew Bull. 25 (1971) 506; Whitmore, Tree Fl. Malaya 2 (1973) 63; Airy Shaw, Kew Bull. Add. Ser. 4 (1975) 43; Kew Bull. 36 (1981) 258; S.S.Larsen in Chayam. & Welzen, Fl. Thailand 8 (2005) 105, Fig. 23, Pl. I: 2; Welzen & P.I.Forst., Nordic J. Bot. 28 (2010) 190, Fig. 2, 3; in Noot., Fl. Males. ser. 1, 20 (2011) 51, fig. 2; Map 1. — Buxus nitidus (Miq.) Hallier f., Meded. Rijks-Herb. 37 (1918) 16. — Longetia nitida (Miq.) Steenis, Blumea 12 (1964) 362. — Austrobuxus nitidus Miq. var. nitidus: Airy Shaw, Kew Bull. Add. Ser. 4 (1975) 43. — Type: Teijsmann HB 769 (holo U; iso L, U), West Coast Sumatra, prope Siboga.

    Choriophyllum malayanum Benth., Hooker’s Icon. Pl. 13 (1879) 62, t. 1280; Merr., J. Straits Branch Roy. Asiat. Soc., Spec. numb. (1921) 333. — Longetia malayana (Benth.) Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.xv (1922) 291; Ridl., Fl. Malay Penins. 3 (1924) 224; Corner, Ways. Trees Malaya 1 (1940) 260. — Syntypes: Beccari PB 3270 (FI, n.v., K), Borneo, Sarawak, Beccari PB 3305 (FI, n.v., K), Borneo, Sarawak, Beccari PB 3329 (FI, n.v., K), Borneo, Sarawak, Beccari PB 3344 (FI, n.v., K), Borneo, Sarawak; Griffith KD 5016 (K), Malay Peninsula; Maingay KD 1404 (K, L) , Malaya, Penang; Maingay KD 1404/2 (K, L), Malaya, Penang; Maingay KD 2253 (K), Malaya, Penang, Government Hill; Maingay KD 2568 (K), Malaya, Malacca; Maingay KD 2568A (K), Malaya, Malacca; Wallich Cat. 7975 (K), Singapore.

    Choriophyllum montanum Ridl., J. Linn. Soc., Bot. 38 (1908) 322. — Longetia montana (Ridl.) Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.xv (1922) 291; Ridl., Fl. Malay Penins. 3 (1924) 224. — Austrobuxus montanus (Ridl.) Airy Shaw, Kew Bull. 25 (1971) 507. — Austrobuxus nitidus Miq. var. montanus (Ridl.) Whitmore, Gard. Bull. Singapore 26 (1972) 51. — Type: L. Wray & H.C. Robinson 5424 (K; reported by Ridley as 5434), Malaya, Pahang, Gunong Tahan.

    Austrobuxus nitidus Miq. var. macrocarpus Airy Shaw, Kew Bull. 25 (1971) 506; Kew Bull. Add. Ser. 4 (1975) 43. — Type: KEP (R. Ismail) 104888 (holo K; iso KEP, n.v., L), Malaya, Selangor, Gunung Berembun, near Bukit Tangga.

 

Austniti-photo.gif (149043 bytes)    Austniti-photoleaf.gif (34376 bytes)    Austniti-photomale.gif (150125 bytes)    Austniti-photofruit.gif (92360 bytes)               

 

(Shrubs to) trees, up to 30 m high, bole up to 6 m, dbh up to 50 cm; branchlets pale straw to greyish to greyish brown, flowering ones 2.5–4 mm diameter, somewhat wrinkled when dry. Indument of brownish hairs. Outer bark smooth to rough to broadly fissured to flaky, greyish white to (dark) grey to greyish brown to dark brown, 1–2 mm thick; inner bark pale yellow to pink to reddish brown to brown, fibrous, 5–10 mm thick; sapwood white to yellowish to pale brown, soft; heartwood pinkish brown to red, hard, dense. Leaves: petiole 4–14 mm long, slightly hairy when young, green to red; blade elliptic to obovate, 1.4–16 by 1–6 cm, length/width ratio 1.9–3.2, margin flat to recurved, with glandular dots, apex emarginate to rounded (to bluntly acuminate), upper surface slightly hairy when young, soon glabrous, smooth, dark green, glossy, lower surface hairy when young, soon glabrous, smooth, lighter green to glaucous to grey-green, shiny; venation generally indistinct to distinct on the lower surface, midrib green to brownish yellow beneath, nerves 6–9 per side. Inflorescences single to up to c. 3 together, cymose, but often thyrsoid, sericeous to subglabrous, staminate ones up to 5.5 cm long, pistillate ones up to 1 cm long, with basally several bracts; bracts triangular, largest ones 1–1.7 by 1–1.4 mm. Staminate flowers 3–4 mm in diameter; pedicel 1.7–6 mm long; sepals (3)4 or 5, ovate, the 2 outer ones 1.2–1.8 by 1–1.5 mm, the 2 or 3 inner ones 1.8–2.2 by 1.5–2.8 mm; stamens (4)5, filaments 1.3–2.8 mm long, white; anthers 0.7–1.2 by 0.7–1 mm, pale to golden yellow; receptacle hairy, yellow to orange. Pistillate flowers 2.7–3.7 mm in diameter, green to red to greenish brown; pedicel 1.5–3.5 mm long, elongating up to 12 mm in fruit; sepals 4–8, ovate, 1–2 mm high by 1.5–2.5 mm wide, apex rounded, 4 outer with 2 smaller, very thick, inner ones thinner, with membranous upper margin; ovary globose to ovoid, 1.2–3 by 1.5–2 mm, subglabrous to hairy, glabrescent, 2–4-locular; stigmas split, up to 1 mm long lobes, shortly papillate above. Fruits globose to obovoid, 10–22 high by 9–16 mm wide, wall generally thin, up to 3 mm thick; column 10–17 mm long. Seeds obovoid, 8–10 by 5–6 by 3–4 mm, shiny dark brown when dry; caruncle black when dry, consisting of straight, short papillae, up to 1.5 mm long, in a tight group.

    Distribution — Peninsular Thailand, Malay Peninsula, Sumatra, Borneo.

« = A. celebicus; = A. dentatus; l = A. nitidus

    Habitat & Ecology — Primary forest, secondary forest, Agathis forest, kerangas, fresh water seasonal swamp, primary and secondary peat swamp forest, riverine forest, montane mossy forest; sometimes along roads and sea shore; soil: acidic sand, peat, clay; bedrock: granite, igneous intrusives, sandstone. Altitude: Sea level up to 2200 m. Flowering and fruiting: whole year through. Fruits eaten by monkeys (Gianno 504).

    Uses — Sumatra: Fruit produces edible oil. Borneo (Sabah): Wood uses for construction purposes (Bajau)

    Vernacular names — Malay Peninsula: Dalet (Semelai). Sumatra: Haoendoloksapot; Kalek manoendjang; Tamasoe harangan; Tonggi tonggi. Borneo: Kalimantan: Kalek lilin, Kasoe; Sabah: Oba suluk (Brunei); Oba sapan(g); Parapat; Susu-sudu (Bajau); Sarawak: Rabong, Ubah banih. English: Penang holly tree (Corner, 1940).

    Note — The two varieties, A. nitidus var. macrocarpum and var. montanum could not be distinguished, because of a continuous range in sizes of the leaf blades (var. montanum with smaller leaves) and fruits (var. macrocarpum with larger fruits). There was also no geocline in these sizes, though plants from higher altitude tend to have smaller leaf blades and smaller fruits. The plants in Thailand and the Malay Peninsula are generally somewhat more hairy when young and the bracts of the axillary buds are larger and more distinct.