Flora of Thailand

Euphorbiaceae

 

53. Leptopus

 

P.C. van Welzen

 

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Genus description

Species description

 

Leptopus

 

Decne. in Jacquem., Voy. Inde Bot. 4: 155. 1836; Pojark., Not. Syst. Herb. Inst. Bot. Acad. Sci. USSR 20: 269. 160; Airy Shaw, Kew Bull. 26: 285. 1972; Whitmore, Tree Fl. Mal. 2: 105. 1973; G.L.Webster, Ann. Missouri Bot. Gard. 81: 40. 1994; Welzen, Thai For. Bull. (Bot.) 28: 56, fig. 7. 2000; Radcl.-Sm., Gen. Euphorbiacearum: 24. 2001; Welzen in Welzen & Chayam., Fl. Thailand 8, 2: 352, 2007; G.L.Webster in Kubitzki, Fam. Gen. Vasc. Pl. 11: 66. 2014.— Lepidanthus Nutt., trans. Amer. Phil. Soc. 5: 175. 1837, non Nees, 1830.— Hexakistra Hook.f., Fl. Br. Ind. 5: 283. 1887.— Thelypetalum Gagnep., Bull. Soc. Bot. France 7: 876. 1924.

 

Thailand: Woody herbs (to subshrubs), monoecious. Indumentum of simple, more or less patent hairs. Stipules late caducous to persistent. Leaves alternate, distichous, simple; petiole reniform, not pulvinate; blade papery, margin entire, upper surface (partly) pilose; venation pinnate, nerves looped and closed near margin, veins and veinlets reticulate, indistinct. Inflorescences axillary fascicles on youngest branchlets, with few flowers of both sexes, staminate ones forming after fruit dehiscence. Flowers pedicellate; sepals 5; petals 5, smaller to larger than sepals; disc 5 or 10 lobed (2 at each side of petal). Staminate flowers: stamens 5, free; pistillode present. Pistillate flowers: pistil 3-locular; ovules 2 per locule; style minute; stigmas almost completely split. Fruits not lobed, capsular; column slender, apically not or hardly broadened. Seeds naked.

    Ten species from India to China, Malesia, Australia, Central America. Classification: subfam. Phyllanthoideae, tribe Phyllantheae, subtribe Leptopinae; intermediate between the genera Andrachne and Astrocasia.

 

Leptopus australis (Zoll. & Moritzi) Pojark., Not. Syst. Herb. Inst. Bot. Acad. Sci. USSR 20: 270. 1960; Airy Shaw, Kew Bull. 26: 285. 1972; Whitmore, Tree Fl. Mal. 2: 105. 1973; Welzen in Welzen & Chayam., Fl. Thailand 8, 2: 353, Fig. 14. 2007.— Andrachne australis Zoll. & Moritzi, Natuurk. Geneesk. Arch. Neerl. Ind. 2:17. 1845.— Andrachne calcarea Ridl., Bull. Misc. Inf. Kew 1923: 361. 1923.— Thelypetalum pierrei Gagnep., Bull. Soc. Bot. France 71: 876. 1924.— ?Andrachne lanceolata Beille in Fl. Gén. I.-C. 5: 537. 1927.— Leptopus calcareus (Ridl.) Pojark., Not. Syst. Herb. Inst. Bot. Acad. Sci. USSR 20: 271. 1960; Airy Shaw, Kew Bull. 26: 285. 1972.

 

Leptaust-habit.gif (59207 bytes)    Leptaust-male.gif (37209 bytes)    Leptaust-female.gif (27215 bytes)    Leptaust-fruit.gif (29386 bytes)

 

Woody herbs (to subshrubs), 10–50 cm high; flowering branches 1–1.5 mm thick, tinged red, hairy. Stipules triangular, 1.2–1.8 by 0.3–0.5 mm. Leaves: petiole 0.3–1.6 cm long, hairy; blade elliptic to somewhat obovate, 1–7.6 by 0.5–3.4 cm, index 2–2.8, symmetric, drying brownish or greyish green, base cuneate to attenuate, apex rounded and mucronulate to shortly acuminate, upper surface (completely to) hairy on midrib and margin, dark green, lower surface subpilose to hairy on venation, light green; nerves 5 or 6. Staminate flowers 2–3 mm in diameter; pedicel 4–12 mm long, slightly hairy, green to maroonish; sepals obovate, 1.3–1.4 by 0.7–1 mm, hairy outside, glabrous inside, green; petals obovate, 0.5–0.7 by 0.2–0.3 mm, glabrous, whitish; disc 5 bilobed glands or 10 separate glands, filiform, 0.7–0.8 by 0.1–0.2 mm, glabrous, whitish; stamens glabrous, filaments 0.6–0.9 mm long, whitish; anthers c. 0.2–0.3 mm, light yellow, with 4 theacae. Pistillate flowers 5–6(–12 in fruit) mm in diameter; pedicel 1.2(–8 in fruit) mm long, pilose, green; sepals ovate, 3–3.2(–5.5 in fruit) by 1.5–2(–3.5 in fruit) mm, margin and outside pilose, subglabrous inside, green; petals minute and sticking to backside of disk lobes, obovate, c. 0.3 by 0.2 mm, glabrous; disc lobes 5, almost completely split and V-shaped, c. 0.8 mm long; ovary 0.6–0.5 by 0.7–0.9 mm, densely pilose, yellowish to light greenish; style c. 0.2 mm long, white to light greenish; stigmas 0.7–0.8 mm long, glabrous except sometimes for some hairs on clavate lobe apices, white to light greenish. Fruits triangular in transverse section, c. 5 by 2.5 mm, shortly pilose, white to light greenish when young; column 1.2–1.5 mm long. Seeds triangular in transverse section, 1.9–2 by c. 1.5 by 1.5 mm, transversely ribbed.

    T h a i l a n d.— NORTH-EASTERN: Phetchabun (Nam Nao), Loei (Tali); EASTERN: Nakhon Ratchasima (Khao Saming); SOUTH-WESTERN: Prachuap Khiri Khan (Khao Luang); SOUTH-EASTERN: Sa Kaeo (Roi Pi), Prachin Buri (Ban Keng), Chon Buri (Khao Khiao), Chanthaburi (Doi Soi Dao Nue, Pong Nam Rawn, Soi Dao); PENINSULAR: Chumphon (Sapli), Surat Thani (Khao Phra Rahu, Khao Tao), Phangnga (Ao Luk), Phatthalung (Khao-Pu-Khao Ya National Park, Khao Hun Tek), Khao Oktalu), Trang (Khao Chom Lem, Ko Chang, Nam Tai), Satun (Khao Nang Dam), Songkhla (Padang Besar).

    D i s t r i b u t i o n.— Thailand, Indochina, Malay Peninsula, Philippines, Java, Tanimbar Islands.

    E c o l o g y.— In shaded places in evergreen forest, deciduous forest, bamboo forest, and thickets; occuring along streams; soil: usually on limestone, but also other soils with deep humus. Altitude 10–900 m.

    N o t e.— The differences between A. australis (not on limestone) and A. calcareus (on limestone) as given by Airy Shaw (1972) completely overlap, the complete range of variation in A. australis is covered by the even more variable A. calcareus (largest and smalles leaf sizes, the lesser and more cuneate leaf bases and the colour varying from brownish to greyish). The suggestion by Airy Shaw that they may be ecotypes can also not be maintained. Therefore, both species are united and no intraspecific classification will be presented.