Family of the fortnight: POLYGONACEAE Distribution: The family includes approximately 46 genera and 1200 species (Mabberley, 2008) from the world and mostly distributed in north temperate regions.
Two subfamilies Polygonoideae and Eriogonoideae are universally accepted based on the presence or absence of the ochrea (sometimes rudimentary in Eriogonoideae). All Indian genera belong to Polygonoideae, a subfamily of almost 790 species defined by the presence of ocreae, a monopodial branching pattern, and lack of involucre. The Eriogonoideae (ca. 330 species) are found only in the New World. (Li Anjen et al., 2003). Description: Members of Polygonaceae are either annual or perennial herbs, shrubs or trees. The leaves are simple, alternate, seldom opposite or whorled, usually entire and revolute, usually in spirals, petiolate to sessile. The presence of ochrea is the most distinguishing feature, but in the subfamily Eriogonoideae, it is either absent or reduced in size. Variation can be seen in the axillary or terminal inflorescence which is composed of simple or branched thyrsi panicle-, raceme- or spike-like in appearance which however, are formed of dichasia or helicoid cymes. The flowers are small, trimerous, hermaphrodite or unisexual with tepals 2-6, forming two whorls of 3 elements or one whorl of 5 elements with characteristic quincuncial aestivation. The number of stamens ranges from 2 to 9 or rarely more whereas the pollen character varies from tricolporate to pantoporate. The ovary is superior 2-4 carpellate (generally 3-carpellate) and unilocular whereas the fruits are an achene which is trigonous or lenticular. Taxonomic treatments: Recently, Sanchez et al. (2011) proposed a new taxonomic classification for Polygonoideae based on molecular data that includes five tribes: Calligoneae, Fagopyreae, Persicarieae, Polygoneae, and Rumiceae. Polygonum s.l. is the largest genus in Polygonaceae and a member of the core eudicots in the flowering plants (Judd et al. 2002). It is represented by about 230 species in the world and distributed mostly in N temperate regions (Li Anjen et al, 2003). The genus (commonly known as Knotweeds) has long been a taxonomic puzzle and is widely debated. The traditional method of classification has led to disagreement among taxonomists with regard to which species should be included in the genus *Polygonum *and which taxa should be elevated to their own genus due to the presence of at least one distinguishing characteristic. (Meisner, 1826, 1856, 1857; Bentham & Hooker, 1880; Dammer, 1892; Gross, 1913 a, 1913b; Jaretzky, 1925; Hedberg, 1946; Roberty & Vautier, 1964; Graham & Wood, 1965; Holub, 1971; Sojak, 1974; Haraldson, 1978; Tzvelev, 1987; Ronse Decraene & Akeroyd, 1988; Hassan, 1991, 1997; Hassan & Khan, 1992; Hong et al, 1998; Ronse Decraene et al., 2000). The biomolecular studies by Cuenound et al. (2002), Lamb Frye & Kron (2003), Kim et al. (2005), Kim & Donoghue (2008) and Sanchez and Kron (2008) have revealed that *Polygonum *s.l. is polyphyletic, and should be divided into several genera. The treatment of subfamily Polygonoideae by Haraldson (1978) Ronse Decraene (1988) have suggested species of *Polygonum *in the broad sense to be segregated into two separate tribes, Polygoneae and Persicarieae. Medicinal Value: Medicinal uses of 31 species belonging to 7 genera Viz. *Calligonium*, *Pteropyrum*, *Polygonum*, *Fagopyrum*, *Rheum*, *Oxyria* and *Rumex*, were recorded by Kirtikar & Basu (1980). Thirty four species of *Polygonum* (*s.l.*) have been reported for medicinal uses (Choudhary et al., 2011). Some useful references: http://www.ingentaconnect.com/content/iapt/tax/2011/00000060/00000001/art00013 http://flora.huh.harvard.edu/china/mss/volume05/Polygonaceae.pdf http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=10717 http://donoghuelab.yale.edu/sites/default/files/174_kim_systbot08_0.pdf http://lnmcp.mf.uni-lj.si/Fago/Fagopyrum/Fagopyrum/Each/Fag(18)/Fag(18)-9.pdf http://archive.bsbi.org.uk/Wats5p177.pdf http://www.biology.sc.chula.ac.th/TNH/archives/v11_no1/21-28%20Chorthip%20TNH%2011-1.pdf http://www.lifesciencesite.com/lsj/life1002/369_B01505life_1002_2664_2670.pdf Regards, Ritesh. Note: Please write me separately for details of the references used in the text above. -- You received this message because you are subscribed to the Google Groups "efloraofindia" group. To unsubscribe from this group and stop receiving emails from it, send an email to indiantreepix+unsubscr...@googlegroups.com. To post to this group, send email to indiantreepix@googlegroups.com. Visit this group at http://groups.google.com/group/indiantreepix. For more options, visit https://groups.google.com/d/optout.
