Author: Albert Spear HitchcockPublisher:
ISBN:
Category : Agrostis
Languages : en
Pages : 152
Book Description
North American Species of Agrostis
Author: Albert Spear HitchcockPublisher:
ISBN:
Category : Agrostis
Languages : en
Pages : 152
Book Description
North American Species of Agrostis
Author: United States. Department of AgriculturePublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
North American Species of Agrostis ...
Author: Albert S. HitchcockNorth American Species of Agrostis (Classic Reprint)
Author: Albert Spear HitchcockPublisher: Forgotten Books
ISBN: 9780260516312
Category : Science
Languages : en
Pages : 144
Book Description
Excerpt from North American Species of Agrostis The present paper is an attempt to classify our knowledge concern ing one of our most perplexing genera of grasses. It deals chiefly with those species found north of Mexico, but includes a few notes on the Mexican species. The preparatory study naturally divided itself into two rather distinct lines - the classification of the species, or taxonomy, and the history of the Species, or nomenclature. Each line presents difficulties, a few of which are discussed below. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.
A Sectional Treatment for the North American Species of Agrostis
Author: Alan Ackerman BeetlePublisher:
ISBN:
Category : Agrostis
Languages : en
Pages : 35
Book Description
North American Species of "Agrostis", by A. S. Hitchcock,...
Author: Albert Spear HitchcockPublisher:
ISBN:
Category :
Languages : en
Pages : 68
Book Description
NORTH AMER SPECIES OF AGROSTIS
Author: A. S. (Albert Spear) 1865-19 HitchcockPublisher:
ISBN: 9781374374065
Category : History
Languages : en
Pages : 142
Book Description
North American species of Agrostis
Author: Albert Spear HitchcockPublisher:
ISBN:
Category :
Languages : en
Pages : 68
Book Description
A Biosystematic Study of Some North American Species of Agrostis L. and Podagrostis (Griseb.) Scribn. & Merr
Author: Curt Gerald CarlbomPublisher:
ISBN:
Category : Agrostis
Languages : en
Pages : 446
Book Description
A taxonomic investigation was made of 24 taxa belonging to the section Trichodium (Michx.) Trin., of Agrostis, and the genus Podagrostis. Experimental methods were employed, including: uniform garden culture of transplants and plants grown from seeds collected in natural populations; breeding studies; physiological and phenological investigations; cytological studies; ecological studies in natural populations. Herbarium exsiccatae including the type material of most of the 24 taxa were studied. In addition, comparative morphological studies were made of several of the taxa in their natural habitats and again in the uniform experimental garden. Twenty-four taxa are recognized in this study. Generic and species descriptions, distributional maps, generic and species keys, photographs of 23 taxa including several types, and photomicrographs of meiotic and mitotic figures of 12 taxa are presented. In addition, the various taxa are discussed individually, and the criteria and concepts used for species delimitation in Agrostis and Podagrostis are presented. Chromosome counts of nine species and two varieties of Agrostis and three species of Podagrostis are reported for the first time. Additional counts of other native taxa confirm earlier published counts. Eleven of the 19 species of Agrostis are hexaploids, four species are known to be tetraploids and two species are octoploids. Two hexaploid groups have been delimited - the A. exarata and A. dieqoensis complexes. The three Podagrostis species, P. aequivalvis, P. humilis and P. thurberiana are diploids, 2n = 14. This chromosome number supports previous morphological evidence that Podagrostis is an independent evolutionary group deserving generic status. Three Old World species of Agrostis, adventive in western North America, have been studied cytologically, and chromosome counts are presented. Agrostis perennans, hitherto unknown in western North America, was collected by the investigator on the Olympic Peninsula of Washington. Putative natural hybridization and introgression were observed between several taxa of Agrostis and Podagrostis, namely: A. diegoensis and A. hallii; A. diegoensis and A. pallens; P. humilis and P. thureriana. Physiological races in P. thurberiana and A. exarata have been studied. Clinal races occur with a north-south distributional pattern in P. thurberiana. Races from southern California flowered under shorter photoperiods, while races from northern California, Oregon and Washington flowered at successively later dates under increased photoperiodic regimes. Mountain ecotypes of A. exarata were obligately long-day plants, while sea-level ecotypes were day-neutral and remontant. Agrostis howellii, a species found near sea level, required a long-day photo-periodic regime and cold vernalization for floral initiation. Autogamy occurs in several of the native species of Agrostis. Facultative autogamy seems to occasion rapid ecotypic and racial diversification with concomitant morphological complexity within the taxa. A tentative phylogenetic scheme is presented. The North American species of Agrostis are believed to comprise two main evolutionary groups; the "primitive" and "derived" species of section Trichodium. The "primitive" taxa are chiefly characterized by: 1) having some species with Old World distributions; 2) more northern and/or widespread distributions; 3) a perennial habit; 4) mostly medium to large anthers; 5) reproducing by allogamy; 6) having tetra-, hexa-, and octoploid chromosome levels; 7) inhabiting mesic and sylvan or bog habitats; 8) occurring on older geological formations and soils. The "derived" species are characterized by: 1) not having any conspecific taxa in the Old World; 2) more southern distributions; 3) being weakly perennial or annual; 4) small anthers; 5) reproducing by autogamy or facultative auto-gamy; 6) having hexa- and octoploid chromosome levels; 7) occupying arid and semi-arid habitats; 8) occurring on newer geological formations and soils.
A Biosystematic Study of Some North American Species of Agrostis L. and Podagrostis (Griseb.) Scribn. & Merr
Author: Curt Gerald CarlbomPublisher:
ISBN:
Category : Agrostis
Languages : en
Pages : 0
Book Description
A taxonomic investigation was made of 24 taxa belonging to the section Trichodium (Michx.) Trin., of Agrostis, and the genus Podagrostis. Experimental methods were employed, including: uniform garden culture of transplants and plants grown from seeds collected in natural populations; breeding studies; physiological and phenological investigations; cytological studies; ecological studies in natural populations. Herbarium exsiccatae including the type material of most of the 24 taxa were studied. In addition, comparative morphological studies were made of several of the taxa in their natural habitats and again in the uniform experimental garden. Twenty-four taxa are recognized in this study. Generic and species descriptions, distributional maps, generic and species keys, photographs of 23 taxa including several types, and photomicrographs of meiotic and mitotic figures of 12 taxa are presented. In addition, the various taxa are discussed individually, and the criteria and concepts used for species delimitation in Agrostis and Podagrostis are presented. Chromosome counts of nine species and two varieties of Agrostis and three species of Podagrostis are reported for the first time. Additional counts of other native taxa confirm earlier published counts. Eleven of the 19 species of Agrostis are hexaploids, four species are known to be tetraploids and two species are octoploids. Two hexaploid groups have been delimited - the A. exarata and A. dieqoensis complexes. The three Podagrostis species, P. aequivalvis, P. humilis and P. thurberiana are diploids, 2n = 14. This chromosome number supports previous morphological evidence that Podagrostis is an independent evolutionary group deserving generic status. Three Old World species of Agrostis, adventive in western North America, have been studied cytologically, and chromosome counts are presented. Agrostis perennans, hitherto unknown in western North America, was collected by the investigator on the Olympic Peninsula of Washington. Putative natural hybridization and introgression were observed between several taxa of Agrostis and Podagrostis, namely: A. diegoensis and A. hallii; A. diegoensis and A. pallens; P. humilis and P. thureriana. Physiological races in P. thurberiana and A. exarata have been studied. Clinal races occur with a north-south distributional pattern in P. thurberiana. Races from southern California flowered under shorter photoperiods, while races from northern California, Oregon and Washington flowered at successively later dates under increased photoperiodic regimes. Mountain ecotypes of A. exarata were obligately long-day plants, while sea-level ecotypes were day-neutral and remontant. Agrostis howellii, a species found near sea level, required a long-day photo-periodic regime and cold vernalization for floral initiation. Autogamy occurs in several of the native species of Agrostis. Facultative autogamy seems to occasion rapid ecotypic and racial diversification with concomitant morphological complexity within the taxa. A tentative phylogenetic scheme is presented. The North American species of Agrostis are believed to comprise two main evolutionary groups; the "primitive" and "derived" species of section Trichodium. The "primitive" taxa are chiefly characterized by: 1) having some species with Old World distributions; 2) more northern and/or widespread distributions; 3) a perennial habit; 4) mostly medium to large anthers; 5) reproducing by allogamy; 6) having tetra-, hexa-, and octoploid chromosome levels; 7) inhabiting mesic and sylvan or bog habitats; 8) occurring on older geological formations and soils. The "derived" species are characterized by: 1) not having any conspecific taxa in the Old World; 2) more southern distributions; 3) being weakly perennial or annual; 4) small anthers; 5) reproducing by autogamy or facultative auto-gamy; 6) having hexa- and octoploid chromosome levels; 7) occupying arid and semi-arid habitats; 8) occurring on newer geological formations and soils