A biosystematic study of some North American species of Agrostis L. and Podagrostis (Griseb.) Scribn. & Merr. Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/pc289n54j

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • 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.
Resource Type
Date Available
Date Copyright
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Academic Affiliation
Non-Academic Affiliation
Keyword
Subject
Rights Statement
Peer Reviewed
Language
Digitization Specifications
  • File scanned at 300 ppi using Capture Perfect 3.0 on a Canon DR-9050C in PDF format. CVista PdfCompressor 5.0 was used for pdf compression and textual OCR.
Replaces
Additional Information
  • description.provenance : Approved for entry into archive by Katy Davis(kdscannerosu@gmail.com) on 2014-04-29T16:31:28Z (GMT) No. of bitstreams: 1 CarlbomCurtG1967_Redacted.pdf: 6370711 bytes, checksum: 2d6ec4cc09cc39e8e6a678c91e36ebcd (MD5)
  • description.provenance : Made available in DSpace on 2014-04-29T16:31:29Z (GMT). No. of bitstreams: 1 CarlbomCurtG1967_Redacted.pdf: 6370711 bytes, checksum: 2d6ec4cc09cc39e8e6a678c91e36ebcd (MD5) Previous issue date: 1966-07-28
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2014-04-23T15:07:03Z (GMT) No. of bitstreams: 1 CarlbomCurtG1967_Redacted.pdf: 6146410 bytes, checksum: 8fe9b811b36890221a89f0a2b1ff8f82 (MD5)
  • description.provenance : Submitted by Alex McFerrin (amscannerosu@gmail.com) on 2014-04-23T20:21:21Z No. of bitstreams: 1 CarlbomCurtG1967_Redacted.pdf: 6370711 bytes, checksum: 2d6ec4cc09cc39e8e6a678c91e36ebcd (MD5)
  • description.provenance : Rejected by Katy Davis(kdscannerosu@gmail.com), reason: Replace on 2014-04-23T20:18:58Z (GMT)
  • description.provenance : Submitted by Alex McFerrin (amscannerosu@gmail.com) on 2014-04-23T00:08:35Z No. of bitstreams: 1 CarlbomCurtG1967_Redacted.pdf: 6146410 bytes, checksum: 8fe9b811b36890221a89f0a2b1ff8f82 (MD5)
  • description.provenance : Approved for entry into archive by Katy Davis(kdscannerosu@gmail.com) on 2014-04-23T20:24:32Z (GMT) No. of bitstreams: 1 CarlbomCurtG1967_Redacted.pdf: 6370711 bytes, checksum: 2d6ec4cc09cc39e8e6a678c91e36ebcd (MD5)

Relationships

Parents:

This work has no parents.

Last modified

Downloadable Content

Download PDF

Items