Leptosiphon Benth. (Polemoniaceae) has 40 taxa, distributed mainly in western North America, with one species in Chile. Phylogenetic studies of Polemoniaceae have consistently supported recognition of Leptosiphon as a separate genus from Linanthus, and resolved an array of taxonomic problems; however, several issues remained unclear for Leptosiphon. In those studies, sampling of Leptosiphon was incomplete, and certain species having strikingly similar floral morphologies appeared non-monophyletic, while other species groups with divergent floral morphologies formed a clade. Our analyses use greater sampling across taxa in Leptosiphon and, in addition to nrITS, the non-coding chloroplast region trnS–trnG to help resolve the genus phylogeny. These results yielded a more complete phylogeny from which to base further research on floral evolution in this group. However, much work remains to be done in resolving species level relationships. Analyses of morphological character evolution suggest that several characters that have been used to define sections within Leptosiphon are misleading. In addition, these data suggest that at least one species (i.e., L. parviflorus) might be polyphyletic.

Slender goldenweed (Xanthisma gracile; synonym Haplopappus gracilis) (2n = 4) is an annual, highly polymorphic, and taxonomically controversial species occurring in the southwestern United States and northern Mexico. It is very similar in morphology to Haplopappus ravenii, but differs in chromosome number, with H. ravenii having 2n = 8. Some botanists have considered these to be separate species in the past, but H. ravenii has not been recognized in the most recent taxonomic treatments of this complex. Numerous researchers have questioned the morphological distinctiveness of these two taxa, but no study has quantified differences in morphology across geographically diverse populations or tested for genetic differentiation between these taxa. The difference in chromosome number suggests that these taxa could be reproductively isolated, which would support recognition of these as unique taxa under the biological species concept. Here, we applied an alternative species concept, the genotypic cluster criterion to test the hypothesis that X. gracile and H. ravenii are distinct species and warrant recognition at this level. Flower and leaf characters were measured on herbarium specimens and genetic diversity was quantified using AFLP's. Little evidence of morphological differences in samples assigned to each species was found as no characters exhibited significantly different means. Genetic differentiation between the two groups of samples was significant in an analysis of molecular variance, but the level of divergence was quite low (φ_ST = 0.015, P < 0.05) in comparison to values for other clearly demarcated species. Clustering analysis did not indicate cleanly separated groups of morphologically or genetically divergent samples. Although this study did not test for reproductive isolation, little evidence was found to indicate that these taxa are divergent, an expected outcome if these species are not exchanging genes. We suggest that X. gracile is a polymorphic species with a varied distribution of cytotypes and should continue to be recognized as a single species.

This paper presents a case study examining the radial-growth history of Sitka spruce (Picea sitchensis) and Douglas-fir (Pseudotsuga menziesii) trees following known and projected high-wind events along the central Oregon coast. Using tree-ring measurements collected from wind-traumatized trees of both species, we identified periods exhibiting negative (−) and positive ( ) radial growth corresponding to canopy breakage (−) and increased light levels following canopy gap formation ( ). Periods of negative and positive growth were then statistically and qualitatively compared across species and against a period of historically documented windstorms (AD 1895–2003) and a 230-year tree-ring derived windstorm record (AD 1775–2003). Our results revealed: 1) both Sitka spruce and Douglas-fir exhibit radial-growth anomalies corresponding to high-magnitude windstorms during the period of historical period, and 2) Sitka spruce is more sensitive and susceptible to wind-induced canopy trauma and exhibits an earlier onset of post-windstorm recovery than Douglas-fir over a >230-year period. These results are consistent with the combined effects of topography and coastal proximity, each species' habitat requirements, and their physiological tolerances to wind stress.

Fungal disease has important effects in natural and agricultural plant populations; however, we are still uncovering factors that influence severity in these systems. Understanding these factors is especially important because it has been predicted that climate change will increase fungal disease widely as a result of changes in precipitation. Here, we investigate the role of water availability and other ecological variables in determining disease severity of a foliar fungal disease. For this study, we focused on natural populations of an important annual, herbaceous plant, Brassica rapa and its fungal disease, Alternaria blackspot. We explored three hypotheses: (1) The factors that drive disease severity differ early in the growing season compared to late in the growing season. (2) Disease severity patterns for this fungus are driven by water availability to a greater extent than other ecological variables. (3) Disease severity increases with plant density. To address these hypotheses, data were collected in a spatially structured manner at two time points during the summer of 2011 from four B. rapa plant populations along the California and Oregon coasts. We found no clear factors drove disease severity early in the growing season, while factors such as host density, herbivory, sun exposure, and host developmental stage influenced disease severity later in the season. We found that soil moisture did not have a clear relationship with disease severity, and that greater host density supported greater disease severity. Our findings suggest that there are many factors influencing fungal disease, and the effects of these factors vary over the course of the growing season. These results have important implications for monitoring and predicting the effects of climate change on plant disease.

Restoration and management of old-growth conditions in coast redwood (Sequoia sempervirens [D. Don] Endl.) forests are traditionally based on an idealized set of characteristics that occur in productive stands. We compared three old-growth sites to quantify variability among remaining reference stands of the central coast redwood range in Mendocino County, California. Two of the sites are protected from coastal influence, have rich alluvial soils, and relatively high visitor usage. The third site is in close proximity to the coast with variable soil conditions and little visitor access. We randomly sampled twenty, 20-meter circular diameter plots in each site to evaluate basal area, tree density, species richness, canopy cover, shrub cover, and herbaceous species cover. We conducted multivariate analyses including nonmetric multidimensional scaling (NMDS), perMANOVA, and indicator species analysis (ISA) to examine the structural clustering and compositional metrics among the sites. Results indicated a strong separation among old-growth reference sites in the NMDS ordination and significant differences in sites using perMANOVA. The inland sites had high tree density, basal area, herbaceous understory cover, and cover of Oxalis oregana Nutt., Adenocaulon bicolor Hook., and Viola glabella Nutt. The coastal site had a high abundance of Trillium ovatum Pursh (an old-growth associated species), high shrub cover in canopy gaps, diverse species assemblages, and relatively high abundance of woodland-adapted perennial species. ISA provided a distinct suite of understory species for each site. The unique characteristics and high variability among these sites may offer a new, and potentially more accurate, standard for restoration and management.

The relationships of Rosa gymnocarpa Nutt. in connection with historical sect. Gymnocarpae Crép. and recent publications on Rosa phylogeny are discussed, noting the relative isolation of the species within the genus. All synonyms and segregate taxa are addressed; a lectotype is designated for the species and other names as needed. Two subspecies are recognized: subsp. gymnocarpa, primarily west of the Cascade-Sierra axis, and subsp. helleri (Greene) Ertter & W. H. Lewis, occurring from southeastern British Columbia and northwestern Montana to the northern Sierra Nevada in California. Subspecies gymnocarpa is further divided into var. gymnocarpa and var. serpentina Ertter & W. H. Lewis. A key, range descriptions, and representative specimens are provided for infraspecific taxa. Extensive zones of intergradation occur where the ranges intersect, especially in the Klamath and Siskiyou ranges of northeastern California and adjacent Oregon; intermediates are also common in northern Idaho and adjacent states and provinces. Presumed hybrids with sympatric species are discussed, including some across ploidy levels. Nothospecies R. ×henryana W. H. Lewis is described for the hybrid of R. gymnocarpa and R. nutkana C. Presl; R. ×collaris Rydb. (pro sp.) is transferred to nothospecies status as the hybrid of R. gymnocarpa and R. woodsii Lindl.

We describe two new subspecies of the widespread shrub Arctostaphylos. One subspecies is a southern extension of A. purissima; A. purissima subsp. globosa V.T. Parker and M.C. Vasey. It differs from the nominate species in several ways, but principally in having glandular hairs on the young stems and inflorescences and having a globose fruit typically with fused nutlets. We also describe a new subspecies of A. patula; A. patula subsp. gankinii M.C. Vasey and V.T. Parker. Arctostaphylos patula subsp. gankinii is a distinctive variant of the montane greenleaf manzanita that occurs widely at various localities in the Sierra Nevada extending into the inner North Coast, Klamath, and Siskiyou ranges of California and southern Oregon. This new subspecies appears to have been identified incorrectly as A. manzanita subsp. roofii and subspecies of A. mewukka in herbarium collections. The patterns of diversity for both species and their subspecies illustrate common taxonomic issues in the genus, representing potential inter-population hybrid introgression and intra-population morphological diversification, a potentially common mode of speciation in this genus.