Arctostaphylos viscida Parry and A. canescens Eastw.,
two well-known and frequently encountered manzanitas in the
Siskiyou Mountains in southwestern Oregon, are shown to
hybridize and to produce an extensive series of morphological
intermediates. The hybridization occurs wherever populations
of these two species meet at contact zones of
serpentine and non-serpentine...
A biosystematic investigation was undertaken in 15
species and three subspecies of the genus Aster, in western
North America. Previous studies had been based entirely on
external morphological features, and it was believed that
much could be learned about the natural affinities of the
taxa by exploring their cytological and...
A study was made of the subgenus Genuini of the genus Juncus in the Pacific States, California, Oregon and Washington. Extensive morphological comparisons, geographical distributions, habitat differences and observations of apparent presence or absence of natural hybrids provided the major data sources. Cytological studies were made, but were inconclusive. Eleven...
This work was performed on Trillium albidum Freeman (Liliaceae), to
clarify the pattern of morphological variation between the small-flowered
populations at the northern limit of its range ( T. parviflorum Soukup) and the
larger-flowered populations from southern Oregon and northern California. It was
hypothesized that only a single species of...
A study was made to clarify the relationships of Mentzelia mollis
Peck and two poorly understood taxa of Mentzelia (Loasaceae) to the
other members of the genus, its sections, and its subsections, and
to describe the general ecology of each taxon.
Within the genus, the section Trachyphytum is characterized by...
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...
Claytonia perfoliata is a west-American polyploid complex of
common annuals (x=6). The species is polymorphic; exomorphic
characters are often variable within local populations. In a transect
of the Columbia River Gorge diploids, tetraploids, hexaploids, octoploids,
and decaploids were collected, which varied in shape of basal
and cauline leaves, degree of...
A biosystematic study was made in seven populations of Mimulus
nanus Hook. & Arn. and M. cusickii (Greene) Piper (Scrophulariaceae)
in central Oregon, and a taxonomic revision was made of the four
species of section Eunanus reported from Oregon--M. nanus, M.
cusickii, M. clivicola Greenm. and M. jepsonii Grant. Mimulus...