Flora of Thailand

Euphorbiaceae

The website deviates from the Flora of Thailand, where Synostemon is still treated as a synonym of Sauropus (the latter presently a synonym of Breynia).

 

82. Synostemon

 

P.C. van Welzen, K. Pruesapan, J.J. Bruhl & I.R.H. Telford

 

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Genus description

Species description

 

Synostemon

 

F.Muell., Fragm. Phyt. Austral. 1: 32. 1858; Airy Shaw, Kew Bull. 26: 343. 1972; Welzen et al., Blumea 59: 89. 2014. Diplomorpha Griff., Notul. Pl. Asiat. 4: 479. 1854.

 

Annual herbs to shrubs, monoecious or dioecious; branches terete or ribbed. Indumentum of simple hairs or absent. Stipules mainly triangular, late caducous. Stem leaves (on orthotropic growth) alternate, mainly laminate on young shouts (to throughout), larger but similar to branchlet leaves, usually scale-like distally (phyllanthoid branching) (to scale-like throughout). Branchlet leaves (on plagiotrophic growth) usually distichous, simple, petiolate; blade symmetric, somtimes scale-like, basally attached, margin entire, surfaces without glands, generally drying greenish; venation usually indistinct, pinnate, veins reticulate. Inflorescences axillary fascicles of single to several bracteate flowers (when older short racemes), pistillate at the top of branches or racemes, staminate at lower nodes, the latter often in short bracteate racemes with a few flowers apically. Flowers actinomorphic, pedicellate, generally hanging down; sepals 6, in two whorls, free to almost completely connate, sexes usually dissimilar, pistillate flowers larger; petals, disc, and pistillode absent. Staminate flowers: sepals free, usually spreading, or connate and cup-like with 6 or 12 lobes, sometimes scales at base of lobes; stamens 3, united into central vertical androphore and apically 3-branched with anthers underneath or not splitting and anthers longitudinally along it, anthers 2-thecate, extrorse. Pistillate flowers: calyx persistent; ovary 3-locular, ovules 2 per locule; style mostly absent, stigmas 3, entire or variously bifid, sometimes completely. Fruits rhegmas, ovoid or ellipsoid, often longer than broad, 6-seeded, cartilaginous; columella persistent. Seeds crescent moon-like, ornamented, ecarunculate.

    A genus of 40 species, mainly present in Australia, one also in New Guinea, and one widespread, ranging from the Mascarenes to S and SE Asia, throughout Malesia to Australia. Classification: Subfam. Phyllanthoideae, tribe Phyllantheae, subtribe Flueggeinae.

 

Synostemon bacciformis (L.) G.L.Webster, Taxon 9: 26, in adnot. 1960; Airy Shaw, Kew Bull. 26: 343. 1972; Welzen et al., Blumea 59: 89. 2014.  Phyllanthus bacciformis L., Mant. Pl.: 294. 1767. Phyllanthus racemosus L.f., Suppl.: 415. 1781. Agyneia impubes Vent., Descr. Pl. Jard. Cels.: 23, tab. 23. 1800. Agyneia bacciformis (L.) A.Juss., Euphorb. Gen. Tent.: 24, t. 6. 1824. Agyneia phyllanthoides Spreng., Syst. Veg. 3: 19. 1826, nom. superfl..  Emblica racemosa (L.f.) Spreng., Syst. Veg. 3: 20. 1826. Diplomorpha herbacea Griff., Not. Pl. As. 4: 479. 1854. Diplomorpha bacciformis (L.) Kuntze, Rev. Gen. Pl.: 693. 1891. Phyllanthus goniocladus Merr. & Chun, Sunyatsenia 2: 260, t. 51. 1935. Synostemon bacciformis (L.) G.L.Webster, Taxon 9: 26. 1960, in adnot.. Sauropus bacciformis (L.) Airy Shaw, Kew Bull. 35: 685. 1980; Welzen, Blumea 48: 345, map 5. 2003; in Welzen & Chayam., Fl. Thailand 8, 2: 529. 2007. Breynia bacciformis (L.) Chakrab. & N.P.Balakr., Bangladesh J. Pl. Taxon. 19: 120. 2012.

 

Synobacc-male.gif (62191 bytes)    Saurbacc-photo1.jpg (42327 bytes)    Synobacc-female.gif (28686 bytes)    Saurbacc-photo2.jpg (46864 bytes)    Synobacc-fruit.gif (34727 bytes)    Saurbacc-photo3.jpg (66996 bytes)    Saurbacc-photo4.jpg (33576 bytes)

 

Herbs to subshrubs up to 50 cm high, glabrous, without asperities, branches with mainly 4 ribs. Stipules triangular, 2.2-3 by c. 1 mm. Leaves: petiole less than 1 mm long; blade elliptic, 6.5-25 by 1.5-7(-13) mm, length/width ratio 1.9-6, pergamentaceous, base rounded, margin entire, without asperities, apex rounded to acute, lower surface somewhat papillate and glaucous; nerves very indistinct. Flowers axillary, green, several in fascicles (staminate) or single (pistillate). Staminate flowers 1.2-1.3 mm in diameter; pedicel c. 0.6 mm long; calyx flat, lobes deeply divided, ovate, 0.4-0.5 by 0.3-0.4 mm, apex entire, rounded, scales present; stamens: androphore c. 0.2 mm high, splitting into 3 arms with stamens underneath; stamens c. 0.2 by 0.2-0.3 mm. Pistillate flowers 4-5.5 mm in diameter; pedicel 3-4 mm long; sepals free, 2-2.8 by 1-1.4 mm; ovary obtruncate, c. 1 by 0.9 mm; stigmas c. 0.5 mm long, upper half split, horizontal. Fruits ovoid, 5-5.2 by 5.5-6.5 mm, green, wih apically lobed rim around stigmas; column c. 3.3 mm long, with ellipsoid thickening above middle till apex. Seeds triangular in section, c. 4.5 by 1.2 mm.

    T h a i l a n d. NORTH-EASTERN: Kalasin (Ban Dong Akka), Maha Sarakham (Payak Pom Pisai); EASTERN: Buri Ram (Khao Phanom Rung), Surin (Tongularonghai), Roi Et (Ban Nam Om, Thung Kula Rong Hai), Ubon Ratchathani; SOUTH-WESTERN: Phetchaburi (Mae Klong), Prachuap Khiri Khan (Khao Tao, Sam Roi Yot); CENTRAL: Bangkok (Bangkhen, Bangkok, Paknam), Samut Prakan (Ban Bang Pu Kao); SOUTH-EASTERN: Chon Buri (Ban Soen, Ko Kram, Tong Brong), Trat (Ban Saphan Hin); PENINSULAR: Surat Thani (Kantuli, Ko Pha-ngan, Ko Samui), Nakhon Si Thammarat , Phatthalung (Lahm Bahm).

    D i s t r i b u t i o n. Mauritius, India (type), Sri Lanka, S. China, S.E. Asia (inc. Indochina), W. Malesia: Malay Peninsula, Bangka, Borneo, Java, Sulawesi, Lesser Sunda Islands, New Guinea and Australia.

Saurbacc-map.gif (94408 bytes)

    E c o l o g y. According to Airy Shaw typical for saline sandy or clayey soil, especially along or near beaches, also recorded to be common in wet, grassy roadsides. Altitude: sea level up to 200(-1800) m.

    V e r n a c u l a r. Thong laeng (ทองแล้ง) (Eastern); ma phrao nok khao (มะพร้าวนกเขา), soi nok khao (สร้อยนกเขา) (Central).

    Note. See second note under Breynia amoebiflora.