Flora of Thailand Euphorbiaceae

 

40. Flueggea

 

C. Barker & P.C. van Welzen

 

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Genus description

Identification key

Species description

Willd., Sp. Pl. 4: 637. 1806; G.L.Webster, Allertonia 3: 273. 1984; Ann. Missouri Bot. Gard. 81: 43. 1994; Welzen, Thai For. Bull. 28: 56, Fig. 5. 2000; Radcl.-Sm., Gen. Euphorbiacearum: 35. 2001; C.Barker & Welzen in Chayam. & Welzen, Fl. Thailand 8, 1: 299. 2005; Petra Hoffm., Kathriar. & Wurdack, Kew Bull. 61: 44. 2006; C. Barker & Welzen, Syst. Bot. 35: 541. 2010; G.L.Webster in Kubitzki, Fam. Gen. Vasc. Pl. 11: 77. 2014.— Richeriella Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.xv: 30.1922; in Engl. & Harms, Nat. Pflanzenfam. ed. 2, 19c: 48. 1931; Airy Shaw, Kew Bull. 25: 489. 1971; Kew Bull. 26: 328. 1972; G.L.Webster, Ann. Missouri Bot. Gard. 81: 44. 1994; Radcl.-Sm., Gen. Euphorb.: 36. 2001; Welzen in Welzen & Chayam., Fl. Thailand 8, 2: 515. 2007; G.L.Webster in Kubitzki, Fam. & Gen. Vasc. Pl. 11: 77. 2014.— Securinega auct. non Comm. ex Juss.: Airy Shaw, Kew Bull. 26: 340. 1972.

Shrubs to trees, monoecious to dioecious. Indumentum absent or of simple hairs, mainly glabrous. Stipules cordate, margin membranous, persistent to caducous. Leaves distichous to spiral, simple, symmetric, petiolate, basally attached, without glands, margin entire, surfaces smooth, glandless; venation pinnate, nerves looped and joined near margin, veins and veinlets reticulate. Inflorescences axillary, either fascicles with many staminate (up to >30) or few pistillate, bracteate flowers, sometimes on almost leafless branches (F. virosa) or spikes or spike-like panicles with separate sexes, axillary, pendent; staminate ones usually branched, with groups of flowers per node; pistillate ones unbranched, with a single flower per node (F. gracilis). Flowers actinomorphic; sepals 5, imbricate, ovate; petals absent. Staminate flowers: stamens 5, free, exserted, filaments slender, anthers 4-celled, latrorse; disc of 5 separate glands, between stamens; pistillode short, filament-like ovary and 2 or 3 recurved styles, apically hooked. Pistillate flowers: disc annular; ovary 3-locular; ovules 2 per locule; style absent to present, stigmas spread horizontally, apically (doubly) lobed. Fruits globular to triangular in transverse view, drupaceous, fleshy capsules, tardily dehiscent, smooth, glabrous; sepals reflexed. Seeds angled, trigonous, ecarunculate or with thin sarcotesta.

    Fifteen species in the Paleotropics up to Japan and Australia and Polynesia. Two species in Thailand. Flueggea was considered to be a synonym of Securinega by Airy Shaw; Securinega s.s. is restricted to 5 species in Madagascar. However, a separation between both taxa is preferred, because, as Webster (1984, 1994) already pointed out, important differences exist in seed morphology and pollen sculpture; moreover, recent wood anatomical research also shows a difference in wood anatomy (Baas, pers. comm.). Recently, Hoffmann et al. (2006) placed Richeriella in the synonymy of Flueggea. Classification: Subfam. Phyllanthoideae, tribe Phyllantheae, subtribe Flueggeinae.

Key to the species

1. Flueggea gracilis (Merr.) Petra Hoffm. in Petra Hoffm., Kathriar. & Wurdack, Kew Bull. 61: 44. 2006.— Baccaurea gracilis Merr., Philipp. J. Sci., Suppl. 1: 203. 1906.— Richeriella gracilis (Merr.) Pax & K.Hoffm. in Engl., Pflanzenr. IV.147.xv: 30. 1922; in Engl. & Harms, Nat. Pflanzenfam. ed. 2, 19c: 48. 1931; Merr., Enum. 2: 411. 1923; Punt, Wentia 7: 26. 1962; Köhler, Grana Palynol. 6: 45, 72, 100, t. 4, fig. 5-8. 1965; Airy Shaw, Kew Bull. 25: 489. 1971; Kew Bull. 26: 328. 1972; Welzen in Welzen & Chayam., Fl. Thailand 8, 2: 515, Fig. 68. 2007.

Shrubs to trees up to 10(—17) m tall, dbh up to 12 cm, monoecious. Bark smooth, pale grey to dark brown. Stipules c. 4 by 1,4 mm, caducous. Leaves spirally arranged; petiole 6—7 mm long, , flattened above; blade elliptic, 8—21 by 3.1—9 cm, length/width ratio 2.3—2.6, coriaceous, base attenuate, margin recurved, apex acuminate to cuspidate, above dark green, underneath light green with yellowish green midrib; venation ± flat above, raised beneath, nerves c. 12 per side. Inflorescences spikes or spike-like panicles with separate sexes, axillary, pendent; staminate ones usually branched, with groups of flowers per node; pistillate ones unbranched, with a single flower per node; staminate ones up to 12.5 cm long, green to white. Staminate flowers c. 1.5 mm in diameter, (sub)sessile; sepals 1.2—1.3 by c. 1 mm, of equal length, margin hyaline; disc gland obtrapezoid, c. 0.2 by 0.2 mm, flat; filaments c. 2.2 mm long, anthers c. 0.5 by 0.3 mm; pistillode with c. 0.6 mm long ovary, style absent, stigmas up to 1.4 mm long. Pistillate flowers unknown, data from fruits: pedicellate, pedicels very long in fruit; sepals c. 1.5 by 1.5 mm. Fruits triangular in transverse view, c. 8 by 5 mm, black when ripe, chartaceous exocarp dehiscing from woody endocarp, wrinkled when dry; column c. 2.5 mm long. Seeds c. 3.5 by 3 by 2 mm, ecarunculate.

    T h a i l a n d.— PENINSULAR: Phangnga.

    D i s t r i b u t i o n.— Hainan (China), Thailand, Philippines (type). Probably also in Borneo, see note.

squares= F. gracilis (dots = F. flexuosa)

    E c o l o g y.— Primary evergreen forest, secondary forest, open scrub; mainly on limestone, but also on loam and sandy clay. Altitude: sea level up to 1000 m.

    N o t e.— Flueggea gracilis is probably conspific with the other species, Richeriella malayana. According to Airy Shaw (1971) the species differ in the length of the leaves, up to 16 cm in F. gracilis and up to 28 cm in R. malayana; and in the degree of branching of the inflorescences, R. malayana highly branching, F. gracilis not or with few branches. However, in both differences there is an enormous overlap. If the two species are united, with gracilis as oldest epithet, then the distribution is no longer disjunct. On Borneo there is a distinct form with larger fruits (no overlap in sizes).

2. Flueggea virosa (Roxb. ex Willd.) Royle, Ill. Bot. Himal. Mts. (1836) 328; Voigt, Hort. Suburb. Calc.: 152. 1845; C.Barker & Welzen in Chayam. & Welzen, Fl. Thailand 8, 1: 301, fig. 75, plate XVI: 4. 2005.— Phyllanthus virosus Roxb. ex Willd., Sp. Pl. 4: 578. 1805.— Xylophylla obovata Willd., Enum. Hort. Berol.: 329. 1809.—  Flueggea microcarpa Blume, Bijdr.: 580. 1825.— Securinega virosa (Roxb. ex Willd.) Baill., Adansonia 6: 334. 1866; Pax & K.Hoffm. in Engl. & Harms, Pflanzenfam. ed. 2, 19c: 60. 1931; Airy Shaw, Kew Bull. 26: 340. 1972.— Securinega microcarpa (Blume) Müll.Arg. in DC., Prod. 15, 2: 434. 1866.— Securinega obovata (Willd.) Müll.Arg. in DC., Prod. 15, 2: 449. 1866.— Flueggea obovata (Willd.) Wall. ex F.-Vill., Novis. App.: 189. 1880.

Shrubs up to 4 m high, dioecious; side branches, especially lower ones often with thorny end. Stipules 1.1—1.7 by 0.7—0.8 mm, margin often fimbriate, persistent. Leaves distichous; petiole 3—6 mm long, c. round; blade elliptic to obovate, 1—8 by 0.6—5 cm, length/width ratio c. 1.6, papery; base usually attenuate, margin flat, apex rounded to slightly acuminate, above dark green, underneath glaucously papillate, light greenish; venation indistinct on both sides, nerves 6—13. Inflorescences fascicles. Flowers: sepals outer two smaller than inner 3. Staminate flowers c. 1.5 mm in diameter, greenish to yellowish, pendulous, sweet scented; pedicel 2—6.5 mm long, pale light greenish; sepals 0.7—1.2 by 0.3—1.1 mm, light greenish with white margin; filaments 1.2—2 mm long, white, anthers 0.3—0.5 by 0.2—0.3 mm, light yellow; disc glands fleshy, yellow; pistillode 1.5—2.3 mm long, basally connate, deeply divided into 3 branches, apical 0.3—0.7 mm bent and stigma-like. Pistillate flowers c. 2 mm in diameter; pedicel 2—12 mm long; sepals 0.7—1 mm diameter, disc annular, thin, entire, 0.7—1 mm diam; ovary c. 1 by 0.8 mm wide; style 0.5—0.7 mm long, stigmas 0.8—1.1 mm long, upper third split. Fruits globular, 3.4—5.2 mm in diameter, white. Seeds 2.2—2.4 by 1.2—1.8 mm, with thin sarcotesta.

    T h a i l a n d.— NORTHERN: Mae Hong Song, Chiang Mai, Chiang Rai, Nan, Lampang, Tak, Nakhon Sawan; EASTERN: Chaiyaphum, Nakhon Ratchasima; SOUTH-WESTERN: Kanchanaburi, Phetchaburi, Prachuap Khiri Khan; CENTRAL: Saraburi, Nakhon Nayok ; SOUTH-EASTERN: Rayong, Chanthaburi; PENINSULAR: Surat Thani.

    D i s t r i b u t i o n.— Tropical Africa and Asia (India: type) to Japan and Australia and Polynesia.

dots = subsp. virosa (stars = subsp. melanthesoides)

    E c o l o g y.— Open evergreen forest, mixed deciduous forest, deciduous or moist scrub jungle, old clearings, road sides; often common; soil: mainly limestone, also sand and granite as bedrock. Altitude: 10—700 m.

    V e r n a c u l a r.— Kangpla (ก้างปลา), kang pla khao (ก้างปลาขาว) (General); daeng nam (แดงน้ำ), kangpla daeng (ก้างปลาแดง), ma taek (มะแตก) (Northern); mae-ko-pla (แมะกอปลา), ta-kho-lo-khue (ตาข่อโลคย) (Karen-Mae Hong Son).

    N o t e s.— 1. F. leucopyrus, mentioned for Thailand by Airy Shaw (1972), is probably restricted to India and Sri Lanka. The specific status of this taxon is doubtful. Sometimes, due to loss of leaves, F. virosa may appear to have spiny branches.

    2. van Beusekom & Phengklai 2643 (Chiang Mai: Fang) is exceptional in being very hairy and in having mainly 4 instead of 5 sepals.