A Population Study Of The Birches Betula Alleghaniensis B Pumila And Their Hybrid

Author : Janet Rogge Dugle
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (142 download)

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Download or read book A Taxonomic Study of Western Canadian Species in the Genus Betula written by Janet Rogge Dugle and published by . This book was released on 1964 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Five western North American birches, Betula fontinalis . B. glandulosa , B. pumila var. glandulifera , B. resinifera and B. papyrifera are studied taxonomically. Synonymy, descriptions, distribution and representative specimens examined are included. Four hybrid taxa, B. x winteri , B. x sargentii , B. x arbuscula, and B. x uliginosa , are described for the first time and three additional hybrids, B>. x utahensis , B. x eastwoodae and B. x sandbergii are also included. When birch species are in contact, they often hybridize. The populations so formed have been analyzed and the nature of several hybrid entities determined. The methods of analysis applied are as follows: chromatography of leaves and bark; hybrid index; polygonal graphs; chromosome numbers; pollen size, morphology and stainability; stomatal size; germination data; and pictorialized scatter diagrams. Betula x uliginosa (2n = 28-56) is the result of hybridization between B. resinifera and B. pumila var. glandulifera . In the population analyzed, introgression was in the direction of B. pumila var. glandulifera , the birch with the higher chromosome number. When B. pumila var. glandulifera is in contact with B. glandulosa , B. x sargentii (2n = 28-56) is produced. Introgression seems to be in both directions, although most of the gene flow is in the direction of the taxon with the higher chromosome number, B. pumila var. glandulifera . B. x eastwoodae (2n = 28) is the result of hybridization between B. glandulosa and B. fontinalis . Introgression was influenced very little by environmental selection, and B. x eastwoodae seemed to be as common as either of the parental species; and any gene flow was in either direction. B. x utahensis (2n = 28-84 with a concentration at 2n = 56) is the result of hybridization between B. papyrifera and B. fontinalis . In populations of these birches, introgression is mainly from B. fontinalis into B. papyrifera . Hybridization of B. x sargentii and B. papyrifera results in B. x arbuscula (2n = 28-84), a rare hybrid. Tentative conclusions are that introgression is in the direction of B. papyrifera , the taxon with the higher chromosome number. Hybridization of B, resinifera and B. papyrifera produces B. x winteri (2n = 28-84 with a concentration of individuals at 2n = 56). In the populations of these birches which were analyzed, introgression was in both directions. B. x sandbergii (2n = 56-84) results from hybridization of B. papyrifera and B. pumila var. glandulifera . As contrasted with the above, and probably as a result of strong environmental influence in the area in which this cross was analyzed, introgression was in the direction of J3. pumila var. glandulifera , the parental taxon with the lower chromosome number.