Taxonomic studies of two major genera Polygonum L. (complex) and Rumex L. of Polygonaceae from Pakistan

Abstract

The detailed taxonomic study of the Complex genus Polygonum L. (segregated into six genera and discussed separately in the present account) and Rumex L. of Polygonaceae has been carried during 2006-2009. Material for morphological, anatomical and palynological studies was obtained from the herbarium specimens and freshly collected material while for Amplified Fragment Length Polymorphism (AFLP) only fresh samples were used. Forty eight species belonging to seven genera, Aconogonon (Meisn.) Reichenb., Bistorta Adans., Fagopyrum Mill., Fallopia Adans., Persicaria Mill., Polygonum L. and Rumex L. were morphologically reviewed in detail, original observations being supplemented by and compared with previously published information. 6 new taxa were described first time in this account and proposed to be the new varieties. These included three varieties of Polygonum aviculare L., two varieties of Polygonum paronychioides C. A. Mey. ex Hohen and one variety of Polygonum polycnemoides Jaubert & Spach. Leaf epidermal studies have been carried out on forty seven species of the family and observations are made through traditional light microscopy. To my knowledge no such work is yet known which has dealt with comprehensive qualitative and quantitative micromorphological foliar investigations in the taxa of Polygonaceae from Pakistan. The study revealed some distinctive anatomical features on adaxial and abaxial leaf surfaces such as epidermal cells outline, single or mixed type of stomata on the single leaf surface and presence or absence of trichomes. The shape of epidermal cells is found to be variable; six different stomatal patterns have been examined, including cyclocytic, pericytic and staurocytic stomata not reported earlier for the family. Variation among glandular and non glandular trichomes is also examined. Glandular trichomes are of peltate, capitate and spheroidal type while five types of non glandular trichomes are also examined. Crystalliferous cells have been reported first time in Rumex nepalensis Spreng. Although analyzed epidermal characters have systematic value but they are likely to be stable at specific and generic level and are not much helpful in generic delimitation.Pollen morphological characters have been investigated by light microscope (LM) and scanning electron microscope (SEM). Both qualitative and quantitative characters including aperture number, pollen shape, size in polar and equatorial view, colpi length, exine and intine thickness and exine sculpturing in both LM and SEM have been observed. The characters employed, have been proved to be useful in classification of the complex genus Polygonum L. into different genera. On the basis of aperture number and exine sculpturing pattern in SEM, 14 main pollen types and 6 subtypes namely, Aconogonon type, Bistorta type, Fagopyrum type, Dumetorum type, Convolvulus type, Persicaria type (further subdivided into three subtypes), Capitata type (subdivided into three subtypes), Plebijum type, Patulum type, Cognatum type, Avicularia type, Chalepensis type, Acetosa and Dentatus type have been identified. These different pollen types are arranged in three parallel directions to establish evolutionary trends in pollen types of seven genera of the family Polygonaceae. To examine inter and intraspecific relationship among 28 accessions of 13 species belonging to four genera, AFLP (Amplified Fragment Length Polymorphism) marker system was first time used. Single primer pair was used to amplify AFLPs and fragments were separated in 6% denaturing acrylamide gels. A total of 131 fragments were analyzed. According to present results, the AFLP knowledge was found to be sufficiently susceptible to identify small level of variations and can differentiate highly interrelated genotypes.