Pakistan Research Repository


Khatoon, Surayya (1991) POLYPLOIDY IN THE FLORA OF PAKISTAN AND ANALYTICAL STUDY. PhD thesis, University of Karachi, Karachi.



Chromosome numbers are determined for 637 plant specimens from Pakistan belonging to 492 species and c. 300 genera in 66 dicot and 9 monocot families. Counts for 406 species are new to flora of Pakistan and counts for 187 species are new to science. Twelve genera are cytologically investigated for the first time. Maximum number of new counts is in the family Compositae (20), followed by Scrophulariaceae (14), Cruciferae, Boraginaceae, Labiatae (12 each) and Apiaceae (10). New cytotypes are reported in Consolida stocksiana (Boiss.) Nevski, Dianthus crinitus Sm., Salsola kali L., Indigofera linnaei Ali, Bupleurum exalratum M. Bieb., Conyza albida Willd. ex Spreng., Artemisia vulgaris L., Scorzonera tortuosissima Boiss., Alisma ,elantago-aquatica L. and Poa annua L. New basic numbers are recorded in the genera Consolida and Cuscuta. Original counts are reported for 26 endemics. In addition to original counts the information about the species known from Pakistan available in other works carried out in Pakistan, Kashmir, neighboring parts of India, Afghanistan and Iran are also incorporated. By pooling all the available data, the overall number of chromoso.nal1y known species in the flora of Pakistan comes to be 1671 that makes 34% of the total angiosperms in our flora. In the larger families of the sample, the highest frequency of intrageneric polyploidy is met with in Gramineae, followed by Cyperaceae, Cruciferae, Compositae, Scrophulariaceae, Boraginaceae, .Labiatae and Papilionaceae. In the larger families, lowest frequency of polyploidy is found in Umbelliferae in this sample. Some smaller families do not show any polyploidy. The families with higher frequencies of lntrageneric polyploidy are found t? be mainly herbaceous in habit and cosmopolitan in distribution, whereas families with greater frequencies of higher basic numbers (though showing little intrageneric polyploidy) are found to be mainly arboreal in habit and tropical in distribution. The overall intrageneric polyploidy in the flora of Pakistan on the basis of present sample is calculated to be 32% and the total polyploidy (i.e. intrageneric plus palaeopolyploidy) is found to be 55% which is considerably lower than the world average. In the phytogeographic analysis of polyploidy, the highest frequency of palaeopolyploidy is met with in the Sino-Japanese element which indicates the antiquity of this flora. In the uni or biregional phytogeographic elements of more humid and tropical areas also the palaeopolyploidy is met with in higher frequencies. In the biregional or pluriregional elements of temperate areas, the difference between intrageneric polyploidy and total polyploidy is found to be lower, that means these elements contain comparatively lower proportions of palaeopolyploids. However, in every phytogeographic region, the families retain their general pattern of the distribution of polyploidy to a greater or lesser extent. Therefore, polyploidy seems to be more correlated with the taxonomic category as compared to other factors

Item Type:Thesis (PhD)
Uncontrolled Keywords:flora, chromosome, dicot families, monocot families, polyploidy, compositae, scrophulariaceae, cruciferae, boraginaceae, labiatae, apiaceae, consolida stocksiana (boiss.) nevski, dianthus crinitus sm., salsola kali l., indigofera linnaei ali, bupleurum exalratum m. bieb., conyza albida willd. ex spreng., artemisia vulgaris l., scorzonera tortuosissima boiss., alisma ,elantago-aquatica l., poa annua l., consolida, cuscuta, gramineae, cyperaceae, cruciferae, compositae, scrophulariaceae, boraginaceae, .labiatae, papilionaceae, polyploidy
Subjects:Biological & Medical Sciences (c) > Biological Sciences(c1) > Paleo-botany(c1.9)
ID Code:1344
Deposited By:Mr. Muhammad Asif
Deposited On:14 Feb 2007
Last Modified:04 Oct 2007 21:06

Repository Staff Only: item control page