Maharajan M and Rajendran A. / Journal of Science / Vol 4 / Issue 3 / 2014 / 144-148.

e ISSN 2277 - 3290 Print ISSN 2277 - 3282 Journal of Science Botany

www.journalofscience.net

TAXONOMIC STUDIES ON SELECTED OF THE GENUS POLYGONUM L. () IN SOUTH INDIA

*Maharajan M and Rajendran A

Department of Botany, Bharathiar University, Coimbatore, Tamil Nadu, India – 641 046.

ABSTRACT A study has been conducted to resolve the taxonomical complexity of Polygonum spp. distributed in South India. Comprehensive exploration trips conducted throughout Western Ghats and 7 Polygonum species were collected. The are properly identified and documented after detailed taxonomic studies. Taxonomic notes of each species are provides along with short note about the habit, habitat, phenology, global distribution and colour photos. A key is also provided for the easy identification of these species.

Keywords: Polygonaceae, Polygonum, South India, Taxonomic studies.

INTRODUCTION Linnaeus [10] when in his first edition of Species Polygonaceae Juss., the Buckwheat, Smartweed Plantarum, he described 26 species of this complex genus. or Knotweed family is a cosmopolitan family, Polygonum species mainly distributed in South, geographically distributed from the tropics to the arctic North and North-East India. So far 13 species were although most species are concentrated in the northern reported from South India [12]. The genus is temperate region [1]. It is the family of dicots containing characterized by its prostrate habit, sometimes approximately 1,200 species in 48 genera [2,3]. The name subprostrate or erect, alternate leaves, presence of ochreae of the family is derived from Greek word “Polygonon”, on nodes, axillary flowers, tepals with only one main “Polys” meaning many and “gonon” meaning Knee vein, stamen in two whorls, outer smaller in size than referring to the prominent nodes of many species [4]. inner, filaments swollen at the base and absence of Members of the Polygonaceae are diverse in habit ranging nectarines [5]. from annual or perennial herbs, shrubs to lianas and some On this context, 7 Polygonum spp. with high trees. The most distinctive feature of the family is the taxonomic complexity were selected for the present study presence of membranous or hyaline sheath uniting the and detailed taxonomic studies were conducted to resolve stipules. the taxonomic problems. The family Polygonaceae is a complex family [5], most diverse in morphology and difficult in MATERIALS AND METHODS [6]. Jussieu [7] accepted the distinctiveness of the family The live specimens were collected from various as a natural group. When problematic taxonomy is geographical areas of Western Ghats viz. Ooty, recognized, we refer to “species complexes” in which Doddapetta, Conoor and Kothagiri, part of Nilgiri variation is not clearly partitioned into distinct taxonomic Biosphere Reserve, Tamil Nadu, Wayanadu, Palakkad units; these are common in plants. The genus Polygonum districts of Kerala, Bangalore, Karnataka and Rajamundri is large and heterogenous unit and recent estimate put the area of Andhra Pradesh etc. The scientific authentification number of species at about 181 [8,9]. At the generic level, of species was done with the perusal of relevant literature, the circumscription of Polygonum is always remained floras and comparison with herbarium specimen deposited confused and as a special challenge since the time of at various herbaria in South India [11-16].

Corresponding Author:- Maharajan M Email:- [email protected]

144

Maharajan M and Rajendran A. / Journal of Science / Vol 4 / Issue 3 / 2014 / 144-148.

Voucher specimens were deposited at Madras Herbaria rarely solitary; bracts funnel-shaped, glabrous, margin (MH) for future studies and reference. A taxonomic key is ciliate, each 3-5-flowered. Pedicel short. Perianth white or also provided to the selected 7 Polygonum spp. to greenish, 5-parted; tepals elliptic, 1.5-2 mm. Stamens 5-8, facilitate the identification of the species. The correct included. Styles 3; stigmas capitate. Achenes included in botanical identity with synonyms, habit, habitat, persistent perianth, black, shiny, ovoid, trigonous, 1.5-2 phenology and global distribution of these 7 species were mm (Plate 1B). given along with colour photos. (Plate1). Polygonum chinense L. RESULTS AND DISCUSSION Habit : Perennial herb The present study is an attempt to resolve the Habitat : Wet valleys, grassy slopes, taxonomic complexity of Polygonum spp. distributed in mixed forests, thickets in South India. Seven species were collected during the valleys, mountain slopes up to study from different agroclimatic zones of South India 2000 m. and detailed taxonomic studies were carried out. The Fl. & Fr. : Jul. - Dec. observations were studied and recorded. Distribution : India, Bhutan, Indonesia, Japan, Malaysia, Myanmar,Nepal, Philippines, Sikkim, Key to the species selected for the study Thailand, Vietnam 1a. Leaf blade lanceolate or elliptic; inflorescence panicle………………………………...... 1. P. barbatum Description of the Species: Herb; perennial, rhizomes 1b.Leaves blades ovate-triangular; inflorescence dense stout. Stems erect, 70-100 cm tall, ligneous at base, much corymbos……………………………..… 3. P. fagopyrum branched, striate, glabrous or retrorsely hispid. Petiole 1-2 2a. Ocrea glabrous, 1.5 – 3 cm; perianth accrescent in cm, usually auriculate at base, upper leaves subsessile; fruit………………………………………. 2. P. chinense leaf blade ovate, elliptic, or lanceolate, 4-16 × 1.5-8 cm, 2b.Ocrea not as above………………………………….2 both surfaces glabrous or hispid, abaxially sometimes 3a. Plants glabrous throughout; pedicel longer than pubescent along veins, base truncate or broadly cordate, bracts………………………………………4. P. glabrum margin entire, apex shortly acuminate; ocrea tubular, 1.5- 3b. Plants not as above………….…………………….. 4 2.5 cm, membranous, glabrous, much veined, apex 4a. Perianth accrescent in fleshy fruit; tepals oblique, not ciliate. Inflorescence terminal or axillary, elliptic……………………………………….. 6. P. molle capitate, 3-5 mm, usually several capitula aggregated and 4b. Perianth not as above………….……………………5 panicle-like; peduncle densely glandular hairy; bracts 5a. Leaves yellow glandular; perianth purplish red or broadly ovate, each 1-3-flowered. Perianth white or white……………………………………..7. P. nepalense pinkish, 5-parted; tepals ovate, accrescent in fruit, 5b.Leaves not yellow glandular; perianth white or pink becoming blue-black, fleshy. Stamens 8, included. Styles above……………………………………5. P. hydropiper 3, connate to below middle. Achenes included in persistent perianth, black, opaque, broadly ovoid, Polygonum barbatum L. trigonous, 3-4 mm (Plate 1C). (syn.: barbata (L.) H. Hara; Polygonum omerostroma (Ohki) Sasaki; P. kotoshoense Ohki; P. Polygonum fagopyrum L. omerostromum Ohki) (syn.: Fagopyrum vulgare Hill; F. sagittatum Gilib.; F. Habit : Perennial herb sarracenicum Dumort.; Polygonum tataricum Lour.; P. Habitat : Stream sides, wet areas, water cereale Salisb.). sides up to 1300 m. Habit : Annual herb Fl. & Fr. : Sep. - Oct. Habitat : Stream sides, wet areas, water Distribution : India, Bhutan, Indonesia, sides and disturbed areas up to Malaysia, Myanmar, Nepal, New Guinea, Philippines, 1200 m. Sikkim, Sri Lanka, Thailand and Vietnam. Fl. & Fr. : Sep. - Nov. Distribution : India, Bhutan, China, Sri Description of the Species: Herb; perennial, Lanka, Thailand and Vietnam rhizomatous. Stems erect, 40-90 cm tall, robust, pubescent, simple or branched above. Petiole 5-8 mm, Description of the Species: Herb; annual, up to 1 m tall, densely hispidulous; leaf blade lanceolate or elliptic- branched, glabrous. Leaves are petiolate, blades are ovate- lanceolate, 7-15 × 1.5-4 cm, both surfaces pubescent, base triangular to triangular, 2-8 cm long, with acuminate tips, cuneate, margin ciliate, apex acuminate; ocrea tubular, bases are cordate or approximately hastate; upper leaves 1.5-2 cm, membranous, densely hispidulous, apex are smaller, sessile. Inflorescences are terminal and truncate, cilia 1.5-2 cm. Inflorescence terminal, spicate, auxiliary, branch in dense corymbose or paniculate cyme. erect, 4-8 cm, several spikes aggregated and panicle-like, Flowers are white or pink, 6 mm in diameter; pedicel is 2-

145

Maharajan M and Rajendran A. / Journal of Science / Vol 4 / Issue 3 / 2014 / 144-148.

3 mm long, articulate; perianths are 3 mm long; 8 Sri Lanka, Thailand, Uzbekistan; Australia, Europe and nectaries are yellow, alternating with stamens; being North America. heterostyly, capitate stigma. Achene is triquetrous, acute angle, longer than 5 mm, more than twice the length of Description of the Species: Herb, annual. Stems erect, the persistent perianths, brown or black-brown, lucid. 40-70 cm tall, much branched, glabrous, dilated at nodes. This species is common buckwheat and is widely Leaves with peppery taste; petiole 4-8 mm; leaf blade cultivated over the northern and to some extent the lanceolate or elliptic-lanceolate, 4-8 × 0.5-25 cm, both southern hemisphere. There are many cultivars or surfaces glabrous, densely brown punctate, sometimes landraces in this species. Their achene forms can vary appressed hispidulous along midvein, base cuneate, greatly, some of them being winged on the angles (Plate margin ciliate, apex acuminate; cleistogamous flowers 1D). present in many leaf axils; ocrea tubular, 1-1.5 cm, membranous, sparsely appressed hispidulous, apex Polygonum glabrum Willd. truncate, shortly ciliate. Inflorescence terminal or axillary, (syn.: Persicaria glabra (Willd.) M.Gomez. Polygonum spicate, pendulous, interrupted below, usually lax, 3-8 cm, portoricense Bertoloni ex Endlicher; slender; bracts green, funnel-shaped, 2-3 mm, margin P. densiflorum Meisner). membranous, sparsely shortly ciliate, each 3-5-flowered. Habit : Annual herb Pedicels longer than bracts. Perianth greenish, white or Habitat : Riverbanks, stream sides, pink above, 5(or 4)-parted, brownish pellucid glandular marshy areas up to 100 m. punctate; tepals elliptic, 3-3.5 mm. Stamens 6, rarely 8, Fl. & Fr. : Jun. - Sep. included. Styles 2 or 3. Achenes included in persistent Distribution : India, Bangladesh, Bhutan, perianth, black-brown, opaque, ovoid, biconvex or Myanmar, Philippines, Sri- Lanka, Thailand, Vietnam; trigonous, 2-3 mm, densely small pitted (Plate 1E). Africa, Australia, North South America and Pacific Islands. Polygonum molle D. Don. Habit : Subshrub Description of the Species: Herb; annual, glabrous Habitat : Slopes, forests, grassy places throughout. Stems erect, 70-100 cm tall, dilated at nodes, and thickets in valleys up to 1200 - 2000 m rarely branched. Petiole 8-10 mm, robust; leaf blade Fl. & Fr. : Aug. - Nov. lanceolate or oblong-lanceolate, 8-18 × 1.5-3 cm, base Distribution : Bhutan, India, Indonesia, narrowly cuneate, margin entire, not ciliate, apex Myanmar, Nepal, Sikkim and Thailand. narrowly acuminate; ocrea tubular, 1-3 cm, membranous, veins numerous. Inflorescence terminal, spicate, 4-12 cm, Description of the Species: Subshrubs. Stems erect, usually with several dense spikes aggregated and panicle- sometimes slightly ascending, 0.9-1.5[-3] m tall, much like; bracts funnel-shaped, not ciliate, usually each 3- or branched, hirsute, retrorsely hirsute or glabrous. Petiole 1- 4-flowered. Pedicel large, longer than bracts, articulate at 1.5 cm, densely pubescent or glabrous; leaf blade apex. Perianth white or pinkish, 5-parted; tepals elliptic, abaxially light green, adaxially green, elliptic or elliptic- 3-4 mm, veins slender, furcate at apex, not curved lanceolate, 10-20 × 3-6 cm, abaxially sericeous, adaxially downward. Stamens 6-8. Styles 2, connate to below sparsely sericeous, densely so along veins or both middle. Achenes included in persistent perianth, black- surfaces glabrous throughout, base cuneate, margin entire, brown, shiny, ovoid, biconvex, 2.5-3 mm (Plate 1A). apex acuminate; ocrea dark brown, tubular, 2-3 cm, membranous, oblique, pubescent or glabrous. Polygonum hydropiper L. Inflorescence spreading, paniculate, large; rachis and (syn.: Persicaria hydropiper (Linnaeus) Spach; branches densely pubescent or glabrous; bracts ovate. P. hydropiper var. diffusa Kitagawa; Pedicel articulate at apex. Perianth white, 5-parted; tepals P. hydropiper var.vulgaris (Meisner) Ohki; elliptic, 1.5-2 mm, accrescent and fleshy in fruit, P. vernalis Nakai; Polygonum hydropiper var. darkened. Stamens 8, included. Styles 3, free; stigmas longistachyum Chang & Li; capitate. Achenes slightly exceeding perianth, black, P. hydropiper var. vulgare Meisner; shiny, ovoid, trigonous, 2-2.5 mm (Plate 1F). P. schini J. Schuster. Habit : Annual herb Polygonum nepalense Meisner Habitat : Riverbanks, stream sides, wet (Syn.: Cephalophilon nepalense (Meisner) Tzvelev; valleys up to 1500 m Persicaria alata (Buchanan-Hamilton ex D. Don) Nakai; Fl. & Fr. : May - Oct. P. nepalensis (Meisner) H. Gross; Distribution : Bangladesh, Bhutan, India, P. alatum (Buch. ex D.Don) Sprengel; Indonesia, Japan, Kazakhstan, Korea, Kyrgyzstan, P. alatum var. nepalense (Meisner) J. D. Hooker; Malaysia, Mongolia, Myanmar, Nepal, Russia, Sikkim, P. nepalense var. adenothrix Nakai;

146

Maharajan M and Rajendran A. / Journal of Science / Vol 4 / Issue 3 / 2014 / 144-148.

P. punctatum Buchanan-Hamilton ex D. Don; glabrous, sparsely yellow pellucid glandular punctate, P. quadrifidum Hay. base broadly cuneate, decurrent along petiole forming Habit : Annual herb wing, margin entire, upper leaves smaller, subsessile or Habitat : Mountain slopes and moist clasping; ocrea brownish, tubular, 5-10 mm, membranous, valleys up to 1600 – 2000 m. apex obliquely truncate, not ciliate, with recurved seta at Fl. & Fr. : May - Oct. base. Inflorescence capitate, included by an involucral Distribution : India, Afghanistan, Bhutan, Indonesia, leaf; peduncle long, glandular hairy; bracts ovate-elliptic, Japan, Korea, Malaysia, Nepal, New Guinea, Pakistan, usually glabrous, margin membranous. Pedicels shorter Philippines, Russia , Sikkim, Thailand and tropical than bracts. Perianth purplish red or white, usually 4- Africa. parted; tepals oblong, 2-3 mm, apex obtuse. Stamens 5 or Description of the Species: Herb, annual. Stems 6, equaling perianth; anthers black-purple. Styles 2, decumbent or ascending, 20-40 cm tall, much branched at connate at base; stigmas capitate. Achenes included in base, rooting at lower nodes. Lower leaves petiolate; persistent perianth, black, opaque, broadly ovoid, petiole 2-3 cm, winged; leaf blade ovate or triangular- biconvex, 2-2.5 mm, densely pitted (Plate 1G). ovate, 3-5 × 2-4 cm, both surfaces sparsely setose or

Plate 1. Polygonum spp. selected for the study. A. P. glabrum Willd.; B. P. barbatum L.; C. P. chinense L.; D. P. fagopyrum L.; E. P. hydropiper L.; F. P. molle D. Don.; G. P. nepalense Meisner

147

Maharajan M and Rajendran A. / Journal of Science / Vol 4 / Issue 3 / 2014 / 144-148.

CONCLUSION future. There is an urgent need for developing the Southern Western Ghats is one of the major hot conservation strategies for these plants in SWG is spot in the world with exotic and native species. From the essential in for future, which may lead to the discovery of present study the authors properly validated and many taxa from here. documented 7 Polygonum species from various parts of Western Ghats. Some of the threatened factors such as ACKNOWLEGEMENTS over exploitation of natural resources and other The authors indebted their gratitude to Professor anthropogenic activities adversely affect the existing and Head, Department of Botany, Bharathiar University, ecosystem it may leads to the rarity of many species in Tamil Nadu for providing the support.

REFERENCE 1. Heywood VH. Flowering Plants of the World, Oxford University Press, Oxford, 1978, 336. 2. Freeman CC and Reveal JL. Polygonaceae. Vol. 5. Flora of North America, Oxford University Press, 2005, 216-221. 3. Sanchez I and Kron KA.. Phylogenetics of Polygonaceae with an on the evolution of Eriogonoideae. Systematic Botany, 33(1), 2008, 87-96. 4. Komarov VL. Flora of USSR. Israel Program for Scientific Translations Jerusalem, 1970. 5. Ronse Decraene, LP and Akeroyd JR. Generic limits in Polygonum L. and related genera (Polygonaceae) on the basis of floral characters. Botanical Journal Linnean Society, 98, 1988, 321-371. 6. Brandbyge, J. Polygonaceae. The families and genera of vscular plants Vol.2, ed. K. Kubitzki et al. Berlin, Springer- Verlag, 1993, 531-544. 7. Jussieu, ALde. Genera plantarum secundum ordines naturales dis posita. Paris, Herrissant & Barrois, 1789. 8. Mabberley DJ. The -Book. A portable dictionary of the Vascular plants. Cambridge, Cambridge University Press, 2005, 306. 9. http,//www.theplantlist.org/browse/P/Polygonaceae/Polygonum. 10. Linnaeus C. Species Plantarum. A Facsimile of the first edition. Volume 1. London. The Ray Society, 1753 11. Hooker JD. The Flora of British India, Vol. V. Reeve & Co., London, 1886, 197. 12. Gamble JS and Fischer CEC. Flora of the Presidency of Madras. Newman and Adlard, London. (Reprint ed. Vol II, 1957. Botanical Survey of India, Calcutta). 1925, 1244. 13. Fyson PF. The flora of the South Indian Hill stations, Vols. 1, 2. Madras, 1932. 14. Henry AN, Kumari GR and Chitra V. Flora of Tamil Nadu, India. Series 1, Analysis. Volume 2. Botanical Survey of India. 1987, 214. 15. Vajravelu E. Flora Palghat District (including Silent Valley National Park, Kerala). Botanical Survey of Inida, Calcutta, 1990. 16. Matthew KM. An excursion flora of Central Tamil Nadu, India. Oxford & IBH Publishing Co. Pvt. Ltd. 1, 1995, 1227- 1230.

148