Malesian Euphorbiaceae Descriptions

87. PLUKENETIA (Euphorbiaceae)

 

L.J. Gillespie

 

Gillespie, L.J. 2007. A revision of Paleotropical Plukenetia (Euphorbiaceae) including two new species from Madagascar. Syst. Bot. 32: 780–802.

 

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Genus description

Sect. Hedraiostylus

Species description

 

Plukenetia L.

    Plukenetia L., Sp. Pl. (1753) 1192; Gen. Pl., ed. 5 (1754) 438; A.Juss. Euphorb. Gen. (1824) 47 (‘Pluknetia’); Mόll.Arg. in DC., Prodr. 15, 2 (1866) 768; in Mart., Fl. Bras. 11, 2 (1874) 332; Benth. in Benth. & Hook.f., Gen. Pl. 3 (1880) 327; Hook.f., Fl. Brit. India 5 (1888) 464; Prain, Fl. Trop. Afr. 6, 1 (1912) 949; Pax in Engl. & Prantl, Nat. Pflanzenfam. 3, 5 (1890) 66, p.p.; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.ix (1919) 12; in Engl. & Harms, Nat. Pflanzenfam. ed. 2, 19c (1931) 141; Jabl., Mem. New York Bot. Gard. 17 (1967) 142; G.L.Webster, Ann. Missouri Bot. Gard. 54 (1968) 293; Philcox, Fl. Trinidad & Tobago 2, 10 (1979) 66; Huft, Ann. Missouri Bot. Gard. 81 (1988) 1105; R.A.Howard, Fl. Lesser Antilles 5 (1989) 82; L.J.Gillespie, Syst. Bot. 18 (1993) 575; G.L.Webster, Ann. Missouri Bot. Gard. 81 (1994) 93; Murillo-Aladana & P.Franco, Euf. Reg. Araracuara (1995) 137; L.J.Gillespie & Armbr., Smiths. Contr. Bot. 86 (1997) 30; Radcl.-Sm., Gen. Euphorbiacearum (2001) 247; L.J.Gillespie, Syst. Bot. 32 (2007) 785; L.J.Gillespie & S.S.Larsen in Welzen & Chayam., Fl. Thailand 8, 2 (2007) 509; G.L.Webster in Kubitzki, Fam. Gen. Vasc. Pl. 11 (2014) 148. —Type: Plukenetia volubilis L.

    Vigia Vell., Fl. Flumin. 9 (1832) t. 128. — Type: Vigia serrata Vell. [= Plukenetia serrata (Vell.) L.J.Gillespie].

    Fragariopsis A.St.-Hil., Leηons Bot. (1840) 426. — Type: Fragariopsis scandens A.St.-Hil. [= Plukenetia serrata (Vell.) L.J.Gillespie].

    Pterococcus Hassk., Flora 25, 2, Bleibl. 3 (1842) 41, nom. cons., non Pall., 1773; Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.xi (1919) 21; in Engl. & Prantl, Nat. Pflanzenfam., ed. 2, 19C (1931) 143; Croizat, J. Arnold Arbor 22 (1941) 423; Backer & Bakh.f., Fl. Java 1 (1963) 490; Airy Shaw, Kew Bull. 26 (1972) 327; Whitmore, Tree Fl. Malaya 2 (1973) 126; Airy Shaw, Kew Bull., Addit. Ser. 4 (1975) 187; Kew Bull. 36 (1981) 340; Kew Bull. 37 (1982) 34; Alphabet. Enum. Euphorb. Philipp. Isl.(1983) 43; Grierson & D.G.Long, Fl. Bhutan 1, 3 (1987) 811; D.Naras., N.Rama Rao & Ravisankar, J. Econ. Taxon. Bot. 13 (1989) 56, fig. 1; Radcl.-Sm., Fl. Zambes. 9, 4 (1996) 210. — Type: Pterococcus glaberrimus Hassk., nom. illeg. [= Plukenetia corniculata Sm.].

    Hedraiostylus Hassk., Tijdschr. Natuurl. Gesch. Physiol. 10 (1843) 141; Cat. Hort. Bot. Bogor. (1944) 234. — Type: Hedraiostylus glaberrimus (Hassk.) Hassk. [based on Pterococcus glaberrimus Hassk. = Plukenetia corniculata Sm.].

    Sajorium Endl., Gen. Pl. Suppl. 3 (1843) 98; Baill., Ιtude Euphorb. (1858) 480. — Type: Sajorium corniculatum (Sm.) D.Dietr. [= Plukenetia corniculata Sm.].

    Tetracarpidium Pax, Bot. Jarhb. Syst. 26 (1899) 329; in Engl. & Prantl, Nat. Pflanzenfam., ed. 2, 19C (1931) 142; Keay, Fl. W. Trop. Afr., ed. 2, 1 (1958) 410.— Type: Tetracarpidium staudtii Pax [= Plukenetia conophora Mόll.Arg.].

    Pseudotragia Pax, Bull. Herb. Boissier, ser. 2, 8 (1908) 635.— Type: Pseudotragia scandens Pax [= Plukenetia africana Sond., according to Webster, 1994; = Plukenetia corniculata Sm., according to Radcliffe-Smith, 2001].

    Eleutherostigma Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.ix (1919) 11, t.3. —Type: Eleutherostigma lehmannianum Pax & K.Hoffm. [= Plukenetia lehmanniana (Pax & K.Hoffm.) Huft & L.J. Gillespie].

    Angostylidum (Mόll.Arg.) Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.ix (1919) 17. —Type: Angostylidum conophorum (Mόll.Arg.) Pax & K.Hoffm. [= Plukenetia conophora Mόll.Arg.].

    Apodandra Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.i (1919) 20; in Engl. & Harms, Nat. Pflanzenfam., ed. 2, 19C (1931) 142. — Type: Apodandra loretensis (Ule) Pax & K.Hoffm. [= Plukenetia loretensis Ule, according to Webster 1994].

    Elaeophora Ducke, Arch. Jard. Bot. Rio de Janeiro 4 (1925) 112. — Type: Elaeophora abutifolia Ducke. [= Plukenetia polyadenia Mόll.Arg.].

 

Lianas, vines, or rarely perennial herbs (P. procumbens), monoecious or rarely dioecious; latex absent; stems twining, sometimes initially erect, or rarely procumbent and sprawling. Stipules small, deciduous. Leaves simple, alternate, evergreen or deciduous, petiolate; blade chartaceous, pinnately, palmately or 3-veined, margins subentire to serrulate or rarely serrate, often with small or minute glandular setae; pair of stipels or small knob sometimes present at petiole-blade junction; 1–6(–10) pairs of flat, usually conspicuous basilaminar glands present near base on blade adaxial surface; scattered smaller laminar glands sometimes present on abaxial surface, usually near margin, rarely present on adaxial surface (only in P. supraglandulosa). Inflorescences racemose thyrses or rarely racemes, axillary or terminal, bisexual with pistillate flower(s) at base and staminate flowers above, or rarely unisexual; flowers in condensed cymules, rarely in lax cymes, or single per node; bracts triangular, small, eglandular or rarely larger and biglandular (P. madagascariensis). Staminate flowers small, typically green, greenish yellow or cream; pedicels present, usually articulated (comprising cyme axis plus true pedicel); sepals 4 or 5, valvate; petals absent; glandular disc absent or present, interstaminal, segmented or annular; stamens 8 to c. 60, free, on convex, subglobose, or elongate receptacle; filaments short to elongate or anthers sessile; pistillode absent. Pistillate flowers pedicellate; sepals 4; petals and disc absent; ovary 4-locular with locules uniovulate, 4-angled to deeply 4-lobed, each angle or lobe carinate and/ or with a tubercle, horn, or laterally compressed wing; styles partly to completely connate, column cylindrical to globose or obovoid, free style arms absent or present, entire to obscurely bifid. Fruit a 4-seeded capsule (usually schizocarpous) or berry, deeply 4-lobed to subglobose, each carpel carinate and/or with central tubercle or wing. Seeds subglobose, ovoid, or lenticular and then laterally compressed, ecarunculate, surface smooth, rough, or verrucate; outer seed coat (testa) thin, persistent or not.

    Distribution — A pantropical genus of c. 20 species of which one species widespread in S Asia and Malesia to Australia.

 

Plukenetia L. sect. Hedraiostylus (Hassk.) Mόll.Arg.

    Plukenetia L. sect. Hedraiostylus (Hassk.) Mόll.Arg. in DC., Prodr. 15, 2 (1866) 772. — Hedraiostylus Hassk., Tijdschr. Natuurl. Gesch. Physiol. 10 (1842) 141.— Type: Hedraiostylus glaberrimus Hassk., nom. illeg. [= Plukenetia corniculata Sm.].

    Pterococcus Hassk., Flora 25, 2, Beibl. 3 (1842) 41, nom. cons. — Plukenetia L. sect. Pterococcus (Hassk.) Benth. in Benth. & Hook.f, Gen. Pl. 3, 1 (1880) 327. — Type: Pterococcus glaberrimus Hassk., nom. illeg. [= Plukenetia corniculata Sm.].

The species of this section may be distinguished from other palaeotropical species by very short styles that are shorter than or equal in length to the ovary, small capsules, and small lenticular seeds. In addition, they may be distinguished from Plukenetia L. sect. Angostylidium Mόll.Arg. by their terminal, leaf-opposed inflorescences, fewer stamens, absence of a staminate disc, and from the Madagascan species group by their stamens with filaments and little expanded staminate receptacles.

Plukenetia corniculata Sm.

    Plukenetia corniculata Sm., Nova Acta Regiae Soc. Sci. Upsal. 6 (1799) 4; L.J.Gillespie, Syst. Bot. 32 (2007) 794, figs. 1, 6; L.J.Gillespie & S.S.Larsen in Welzen & Chayam., Fl. Thailand 8, 2 (2007) 510, fig. 66. — Hedraiostylus corniculatus (Sm.) Hassk., Cat. Hort. Bogor Alt. (1844) 234. — Sajorum corniculatum (Sm.) D.Dietr., Synops. Pl. 5 (1852) 331. — Pterococcus corniculatus (Sm.) Pax & K.Hoffm. in Engl., Pflanzenr, IV.147.ix (1919) 22; Backer & Bakh.f., Fl. Java 1 (1963) 490; Airy Shaw, Kew Bull. 26 (1972) 327; Whitmore, Tree Fl. Malaya 2 (1973) 126; Airy Shaw, Kew Bull., Addit. Ser. 4 (1975) 187; Kew Bull. 36 (1981) 340; Kew Bull. 37 (1982) 34; Alphabet. Enum. Euphorb. Philipp. Isl.(1983) 43; Grierson & D.G.Long, Fl. Bhutan 1, 3 (1987) 811. — Type: Rumphius, Herb. Amboin. 1 (1751), Tab. 79, Fig. 2. (between pages 193 and 194), Indonesia, Moluccas, Ambon Island, ‘‘Bagulae Regione’’.

 

Monoecious vine or slender liana; stems twining, sparsely to moderately pubescent, becoming woody. Stipules narrowly triangular or lanceolate, 1.2–2(–2.8) mm long. Leaves evergreen; petioles [1- ; square brackets refer to collections from Timor] 2–8(–13) cm long, moderately or sparsely pubescent; blades ovate, triangular-ovate, oblong-ovate, or elliptic [4–]7–16 by [2–]4–11 cm wide, thin chartaceous, very sparsely pubescent or glabrescent with major veins usually sparsely or moderately pubescent above, base cordate with U-shaped sinus [0.1–]0.5–2.3 cm long, margins finely serrate or rarely serrate, apex acute-caudate with tip 0.6–2.3 cm long; venation palmate, secondary veins semi-craspedodromous, 2–3(4)[–5] on each side of midrib, tertiary veins percurrent or sometimes reticulate; stipels 2, c. 0.5–1 mm long, usually strongly curled adaxially; basilaminar glands 2, circular or elliptic, [0.3–]0.5–1 mm in diam, marginal; laminar glands absent. Inflorescences narrow racemes, 1.5–5 cm long, bisexual, terminal but appearing leaf-opposed, sometimes terminal on short shoots, or rarely axillary (some Thai collections), axes puberulous; peduncle 1–8 mm long; flowers 1 (rarely 2) per node, pistillate flower 1 at basal-most node, staminate flowers numerous above; bracts narrowly triangular, c. 1 mm long. Staminate flowers: pedicel 1.3– 2.5 mm long, glabrescent; bud globose, obtuse at apex; sepals 4, elliptic or ovate, 0.7–1.1 by 0.5– 0.8 mm, sparsely pubescent near base, acute at apex; androecium globose, 0.4–0.6 by 0.6–0.8 mm, comprising 8–14 stamens on small globose or convex receptacle; filaments conical, c. 0.1 mm long; disc absent. Pistillate flowers: pedicel 1.5–9 mm long, sparsely puberulous to glabrescent; sepals narrowly triangular or lanceolate, 1.2–2.2 by 0.5–1 mm, glabrescent; ovary 1–2.5 mm in diam (excluding wings), sparsely or very sparsely puberulous with puberulent medial line on each carpel extending along wing margin, 4-winged, wings 0.5–2 mm long, elongating to 13 mm and becoming glabrescent in immature fruit stage; styles completely connate into a small depressed-globose column, 0.5–0.7 by 0.8–1.1 mm, glabrous, with cross-shaped stigmatic surface at apex. Fruits 4- lobed capsules, [5–]7–11 by 15–20 mm, glabrescent, surface irregularly verrucate, each carpel lobe with central strap-shaped wing of 6–12 by 2–3 mm; pedicel [0.6–]2–5 cm long. Seeds broadly lenticular, 8–11 by 6.5–8 3 5–6.5 mm, obtuse-triangular in outline, laterally compressed, with radial keel 0.3–0.7 mm wide, surface smooth, cream, pale orange-brown, or pale to medium brown with dark orange or dark brown irregular markings; testa persistent.

    Distribution — Widespread but uncommon throughout SE Asia and Malesia, in NE (Assam) and SE (Andhra Pradesh) India (Narasimhan et al. 1989), Burma (?), Thailand, Philippines, Malaysia, and Indonesia. Also recorded, but not confirmed, from Sikkim in NE India (Grierson & Long, 1987) and Bangladesh (Huq 10780, L).

    Habitat & Ecology — A slender twining liana found in clearings and other disturbed areas of lowland wet (evergreen) and moist (deciduous) forest, sometimes cultivated. Alt.: 50–550 m. Flowering:June in Bangladesh, August in India, December in the Philippines, July and August on Borneo, and throughout the year on Java and Sumatra; fruiting: August in India, July and September in Thailand, June on the Malay Peninsula, December in the Philippines, June and August in Sarawak, October in Sulawesi, and April to August in Java and Sumatra. Reported to be the larval foodplant of the Nymphalid butterfly, Ariadne isaeus, in Malaysia (Kirton T.22).

    Pollen — See Gillespie, Ann. Missouri Bot. Gard. 81,1994: 325, figs. 14–24.

    Uses — The species is recorded as cultivated in Sarawak and Sumatra. In Sarawak young shoots, leaves, and young fruits are recorded to be eaten as a vegetable, while the mature seeds are eaten as nuts and are said to taste similar to peanuts (Chin See Chung 2712, Christensen & Apu 318). It is reported to be cultivated as a vegetable by Dayaks and the distinctive form of the fruit is sometimes seen tatooed, 5 or 6 in a vertical row, on the back of an Iban (Smythies 14073). In India a paste made from young leaves is used as an oral laxative medication (Narasimhan et al., 1989). In Australia the species was collected under cultivation in a garden, where it was called Borneo pea (Waterhouse 5980).

    Vernacular names — Sumatra: Gandi riman; Paina paina; Pepina; Pina-pina makanan. Java: Aroj tangtang anging. Borneo: Sarawak: Buah andu (Iban); Buah palidung (Kelabit); Laot (Kenyah). Lesser Sunda Islands: Aroy tangtang angien; Flores: Lanteng wasι.

    Notes — 1. The species may be easily distinguished from other members of P. sect. Hedraiostylus by its prominently 4-winged capsule and larger leaf blades with a distinctly cordate base. Leaves are also distinct in their long petioles (2–8 cm long), caudate apex, and prominent basilaminar glands and stipels. Styles are completely connate, and both stylar column and filaments are shorter than in the other two species. This is the only species of Plukenetia known from Asia.

2. Plukenetia corniculata was the second species of Plukenetia, after the neotropical Pl. volubilis, to be illustrated (Rumphius, 1741, as ‘‘Sajor volubilis’’) and formally described (Small, 1799). However, for much of its history, the species has been known under a variety of other names. Hasskarl (1842) based his new genus Pterococcus on this species, but renamed the species ‘‘Pterococcus glaberrimus’’, an illegitimate name being based on Pl. corniculata. Soon after, Hasskarl (1843) created a second genus, Hedraiostylus, and transferred the species, naming it ‘‘Hedraiostylus glaberrimus’’, again an illegitimate name. Later legitimate combinations include Hedraiostylus corniculatus, Sajorum corniculatum, and Pterococcus corniculatus, the last used by Pax and Hoffmann (1919) and by most subsequent authors.

3. The species is most densely distributed on the island of Sumatra and less so on Borneo. Distribution outside this area appears to be scattered and sparse. The reason may be that it is rarely collected due to its naturally sparse distribution in these peripheral areas and its vine habit. An alternative explanation may be that it was introduced and cultivated and/or naturalized in at least some of these areas for its edible seed. Many of the collections from these areas are old and some are recorded as cultivated. All collections seen from Timor (pre-1829 based on determinations by A. Zippelius), Java (numerous collections, all pre-1923, and all but one likely cultivated), Sulawesi (one collection, 1929), and the Moluccas (type collecton only, pre 1800) are old, as are most from Assam, India (all but one pre-1890 or undated). The record from Burma could not be verified, since contradictory locality information is given on the only collection seen, Griffith 4716 (Mergui [Burma] on one sheet, Malakka [Malaysia] on two sheets at K; undated). Four of five collections from Sarawak were recorded as cultivated or from gardens or house compounds.