Graduate Thesis Or Dissertation

 

Ecology and reproduction in Collomia macrocalyx Brand (Polemoniaceae) Public Deposited

Downloadable Content

Download PDF
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/5d86p281q

Descriptions

Attribute NameValues
Creator
Abstract
  • Populations of Collom ia macrocalyx Brand were located and observed in order to determine the distribution, ecology, and reproductive biology of this species and probable relationships to other members of the genus. The purpose of the study was to obtain information that would explain the restricted range of the species and would guide in making recommendations for management and conservation. Collomia macrocalyx is endemic to eastern Oregon "scablands." Until recently it was known from only a few widely disjunct sites, and it had been proposed as an "endangered species." A total of 13 extant populations have now been identified. These are all in sites that are fairly uniform in climate, soils, and associated vegetation. The usual habitat for the species is in deep rock crevices on south-facing slopes or ridgetops. Collomia macrocalyx is morphologically the most advanced and biochemically the most distinct species within the genus. It is an annual with a chromosome number of n=8. Vegetatively C. macrocalyx most closely resembles C. tinctoria, while its floral morphology is more like that of C. linearis. Plants grown under greenhouse conditions have vegetative parts which are larger than those of native populations, and they differ in the frequent occurrence of toothed leaves. A new species of Collomia, discovered during the course of this study, appears to be related to both C. macrocalyx and C. tinctoria. The seeds of C. macrocalyx require a two to three month dormancy but germinate readily in nature after autumn rains begin. The plants remain vegetative through the winter months. Many individuals die at the onset of renewed growth in the early spring. Larger individuals are encountered more frequently in deep rocky areas than in open soil. These sites may be cooler and moister, and may offer less competition from other species. Flowering begins in mid-April; the flowers are autogamous, and seed-set is rapid. Most individuals die at the onset of summer drought. Although no pollinators were observed, the presence of some exserted stigmas would allow for occasional out crossing. Seeds are actively ejected from their capsules upon maturation, the dispersal distance being usually less than 10 cm. Most seeds fall into crevices among rocks where they are unavailable for long-distance dispersal. Mucilaginous seedcoats may assist in their dispersal to a new site. Predation and disease have a minimal effect on survival and reproduction. The restricted range of C. macrocalyx is explained by its low dispersal rate away from the parental sites, and its inability to establish itself in habitats where it must compete with other plant species. Though some populations are threatened by human activities, several sites are well protected and the species does not warrant listing as "endangered." Collomia macrocalyx should, however, be monitored to guard against the threats which do exist at some sites.
Resource Type
Date Available
Date Copyright
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Academic Affiliation
Non-Academic Affiliation
Rights Statement
Peer Reviewed
Language
Digitization Specifications
  • File scanned at 300 ppi (Monochrome) using ScandAll PRO 1.8.1 on a Fi-6670 in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
Replaces
Additional Information
  • description.provenance : Made available in DSpace on 2013-08-01T23:38:31Z (GMT). No. of bitstreams: 1 JoyalElaine1984.pdf: 609347 bytes, checksum: e2e8564ea53db1f9008b0d59ea3390ff (MD5) Previous issue date: 1983-10-18
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2013-07-31T15:26:36Z (GMT) No. of bitstreams: 1 JoyalElaine1984.pdf: 609347 bytes, checksum: e2e8564ea53db1f9008b0d59ea3390ff (MD5)
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2013-08-01T23:38:30Z (GMT) No. of bitstreams: 1 JoyalElaine1984.pdf: 609347 bytes, checksum: e2e8564ea53db1f9008b0d59ea3390ff (MD5)
  • description.provenance : Submitted by Katy Davis (kdscannerosu@gmail.com) on 2013-07-30T22:23:00Z No. of bitstreams: 1 JoyalElaine1984.pdf: 609347 bytes, checksum: e2e8564ea53db1f9008b0d59ea3390ff (MD5)

Relationships

Parents:

This work has no parents.

In Collection:

Items