A well-supported phylogeny is presented from both chloroplast DNA (the trnL/F region) and two regions of nuclear rDNA (ITS [internal transcribed spacer] and ETS [external transcribed spacer]) with nearly complete sampling for Mimulus (Phrymaceae) in western North America. Three separate genera are derived from within the clade that contains all the Mimulus species in western North America. The taxonomic status of the proposed sections of Mimulus and the relationships of many taxonomically difficult species are considered with observations on morphological evolution. Discordance between data sources provides support for the hypothesis that M. evanescens is a hybrid between M. latidens and M. breviflorus. In two major clades (Eunanus and Diplacus), patterns of genetic variation do not match the current taxonomy. The clustering of taxa in Eunanus is strongly associated with geographic distributions. Mimulus aurantiacus sensu Thompson, M. nanus, and M. floribundus are found to be progenitor species to other species that appear to be derived from within them. Polyploidy and aneuploidy events are clustered near the tips of the phylogeny. Thus, these two mechanisms are concluded to have played a relatively small role in the evolution of persistent lineages in Mimulus. The phylogenetic distribution of rare taxa is also examined.

Yellow starthistle is an exotic invasive weed that is estimated to infest over 14 million acres in California and is considered the most common exotic weed statewide. We reviewed several previous studies and conducted a township survey to provide an up-to-date analysis of the weed's rapid spread throughout the state. A county-by-county comparison between 1985 and 2002 showed increases in yellow starthistle in all regions of the state except for northeast California and the southeast desert region. Currently, most infestations occur in Northern California, but future invasions and spread will likely occur in the coastal counties of Southern California.

Yellow starthistle (Centaurea solstitialis L.) is a major rangeland weed pest in California and other western states. Two complementary aspects of seed biology were examined: germination and seed bank dynamics. Achenes were tested for changes in germinability over time using various light, temperature, and moisture treatments. Soil cores were collected over time to monitor changes in achene density. Both plumed and nonplumed achenes exhibited photo reversible responses to red and far-red light. White and red light enhanced germination above that occurring in darkness. Achenes showed seasonal changes in germinability, which were characteristic of conditional dormancy. Exposure of achenes to field conditions during summer alleviated primary dormancy, allowing germination to occur at higher temperatures and lower substrate moisture. Nonplumed achenes collected in winter showed reduced germinability at or above moderate temperatures under both single and multiple light exposures. Imbibition and moderately low temperatures with subsequent drying induced secondary conditional dormancy in some achenes. Plumed achenes dominated the soil seed bank before the rainy season, then declined rapidly following rain. Nonplumed achenes peaked after rains began, then declined. Although nearly all achenes were depleted after 4 years, both types remained, showing annual cycles of high and low germinability in autumn and late spring, respectively.Key words: light, phytochrome, conditional dormancy, longevity.

The ranges and abundances of species that depend on freshwater habitats are declining worldwide. Efforts to counteract those trends are often hampered by a lack of information about species distribution and conservation status and are often strongly biased toward a few well-studied groups. We identified the 3,906 vascular plants, macroinvertebrates, and vertebrates native to California, USA, that depend on fresh water for at least one stage of their life history. We evaluated the conservation status for these taxa using existing government and non-governmental organization assessments (e.g., endangered species act, NatureServe), created a spatial database of locality observations or distribution information from ~400 data sources, and mapped patterns of richness, endemism, and vulnerability. Although nearly half of all taxa with conservation status (n = 1,939) are vulnerable to extinction, only 114 (6%) of those vulnerable taxa have a legal mandate for protection in the form of formal inclusion on a state or federal endangered species list. Endemic taxa are at greater risk than non-endemics, with 90% of the 927 endemic taxa vulnerable to extinction. Records with spatial data were available for a total of 2,276 species (61%). The patterns of species richness differ depending on the taxonomic group analyzed, but are similar across taxonomic level. No particular taxonomic group represents an umbrella for all species, but hotspots of high richness for listed species cover 40% of the hotspots for all other species and 58% of the hotspots for vulnerable freshwater species. By mapping freshwater species hotspots we show locations that represent the top priority for conservation action in the state. This study identifies opportunities to fill gaps in the evaluation of conservation status for freshwater taxa in California, to address the lack of occurrence information for nearly 40% of freshwater taxa and nearly 40% of watersheds in the state, and to implement adequate protections for freshwater taxa where they are currently lacking.

Centciurea solstitialis L. is a winter annual weed of Eurasian origin that is widespread in the western United States. Capitula produce dimorphic achenes that are dispersed at different times. Factors investigated in the laboratory that affected germination were light, temperature, achene type (plumed and nonplumed), collection date, dormancy, and storage. The presence of large interactions among the factors affecting germination was constant throughout these studies. Although some germination occurred in the dark, a daily (8 h light: 16 h dark) photoperiod of white light produced higher germination percentages in both fresh and stored achenes. Even a single brief (10-min) exposure to light was almost comparable with a daily 8-h photoperiod. Maximum germination of nearly 100% was achieved in light under constant temperatures of 10, 15, and 20 °C and alternating temperatures of 15:5 and 20:10 °C. Broadening of temperature optima related to afterripening occurred for July achenes stored for 2 months and August-fresh achenes under alternating temperatures. Germination differences between achene types were more prevalent under dark than under light conditions. In general, germination of plumed achenes was higher than that of nonplumed achenes. In darkness, nonplumed achenes showed a shift in optimum germination temperature (from 15 to 20 °C) from July to September. Germination of nonplumed achenes in intact capitula was never greater than 21%, regardless of time of collection, because of the presence of the involucral bracts. Key words: yellow starthistle, germination, light, temperature, dimorphic achenes.