A light and electron microscope study of Corylus avellana L.
vegetative buds infested with the eriophyoid mites, Cecidiophyopsis
vermiformis Nal. and Phycoptella avellanae Nal., is reported. Descriptions
are given of changes in infested stipule tissue. The
nipple-like proliferations (enations) which arise on the infested
stipule surface are covered by a...
The pathogenicity of A. flavus on alkali bee larvae was studied
using sample materials from three nesting sites of these soil
inhabiting bees along the Oregon-Washington state line. Soil
saprophytes of the biosphere of the alkali bee were also studied.
Field observations and direction of soil cores from bee beds...
The developmental cytology of the elaiosome of
Dicentra formosa (Andr.)Walp. was investigated from the
time of initial differentiation until complete maturation.
Light and transmission electron microscopy studies
showed that the elaiosome becomes differentiated from
epidermal tissue in the prefertilized ovule. At this time
the cells are characterized by their large...
Increased temperatures due to anthropogenic-induced climate change may raise the threat of extinction for taxa with sessile life histories (e.g., plants) in the near future. Linking climate change models to demographic models may provide useful insights into the potential effects of environmental changes on rare plants, and therefore aid in...
A greenhouse experiment was conducted in 1991 and in
1992 to determine the effect of soil water pressure on
potato (cv Russet Burbank) plant growth and infection by
Verticillium dahliae. Soil water pressures of -0.01,
-0.03, -0.08, or -0.15 MPa were combined factorially with
two inoculum concentrations, 0 or 10...
Large organic debris has important biological and physical
roles within the stream ecosystem. In order to determine the source
area of large organic debris in streams, thirty-nine streams in the
Cascade and Coast Ranges of Oregon and Washington were sampled. The
distance from point-of-origin to channel was measured for thirty...
Lily hybrids vary in their ability to produce
virus-free (VF) bulblets when grown from virus-infected
scales in tissue culture. Asiatic hybrids typically
produce a higher percentage of in vitro VF scale bulblets
than do Lilium longiflorum cultivars. Three hypotheses
concerning the cause of this variation are tested on five
lily...
Debris flows are a major cause of disturbance to riparian vegetation. Both observational and experimental studies were used to examine the initial recovery of riparian vegetation after debris flows on headwater streams in the western Cascades of Oregon. My goal was to determine the roles of seedlings and vegetative sprouts,...