The understanding of evolutionary relationships in Arctostaphylos has been hampered by taxonomic difficulties in this large and complex genus. A phylogenetic analysis of sequences from the ITS region for 38 species was used to provide a phylogenetic perspective for interpreting evolutionary patterns and relationships in Arctostaphylos. Phylogenetic relationships were estimated using maximum likelihood and Bayesian inference. ITS sequence data do not support a previously published subgeneric classification based on morphological characteristics, but do support the two lineages of Arctostaphylos described by a previous molecular phylogeny based on RFLP data. Topology tests indicate morphological characters are not useful in defining monophyletic clades.

Clarkia stellata Mosquin (Onagraceae) is an uncommon annual herb endemic to Plumas and Yuba Counties in northeastern California that has threatened populations due to noxious weeds, recreational and forest management activities, and development. The purpose of this study is clarify the species identification of populations of Clarkia stellata for management purposes, specifically, populations of C. stellata and C. rhomboidea that are difficult to differentiate in the field. A total of 11 populations of C. stellata and related species were sampled for morphometric analyses and nine populations were sampled for genetic analysis using amplified fragment length polymorphisms (AFLPs). Clarkia stellata can be separated from C. rhomboidea based on all floral characteristics except claw width, claw length, and isthmus width. These species also can be differentiated based on the following vegetative characteristics: petiole length, leaf length, leaf width, and plant height. The sympatric Clarkia mildrediae is easily differentiated from C. stellata by every character except petiole length, leaf length, and plant height; C. mildrediae differs from C. rhomboidea for all characters except petal speckling, pollen color, leaf width, and leaf length. Populations that were initially difficult to categorize as either C. stellata or C. rhomboidea were most similar to C. stellata; however, we were not able to identify a suite of characters that would distinguish these populations as either C. stellata or C. rhomboidea. An analysis of molecular variance (AMOVA) shows that although there was genetic variation among all populations (13.19%), the majority of variation is found within populations (86.81%). Genetic differentiation among all populations was low as calculated by Genetic Data Analysis (Φ_st = 0.132) and Hickory (θ^B = 0.0137); variance within populations was high (sigma-G = 32.645) and between populations was low (sigma-P = 4.96).

This work is consistent with a number of studies within Clarkia section Myxocarpa that have identified taxonomic difficulties due to recent speciation, local adaptation, rapid chromosomal evolution, sympatry, and hybridization.

The floral biology of Fouquieria splendens (Fouquieriaceae), a drought-deciduous shrub with wandlike branches, was studied in the northern Sonoran Desert. Two different measures of plant size, number of branches long enough to flower (>1 m in length) and actual number of reproductive branches, were used to examine the effect of plant size on reproductive output and floral display. Number of flowers and fruits increased with either measure of plant size. Annual flower production ranged from 190 to 6465 per plant and averaged 2553. Annual fruit production ranged from 9 to 1760 per plant and averaged 390. Because some branches long enough to flower did not do so, number of reproductive branches was a stronger predictor of flower production than number of branches > 1 m long. Inflorescence size (mean number of flowers per panicle) was not significantly related to plant size (number of flowering branches) in 2002 or 2003; in fact, the range in inflorescence size on certain individual plants was about as wide as the range for the entire sample. Interannual variation in floral parameters was examined by monitoring the same set of branches in two years, one unusually dry, one with nearly normal rain. In 2002, the dry year, panicles were numerous and sparsely flowered; in 2003, the wetter year, panicles were relatively few and much more densely flowered. Although flowers appeared normally abundant in the wetter year, mean number of flowers per branch was in fact 39% lower than in the dry year. Percent fruit set per panicle in 2003 (36%) was more than twice that in 2002 (16%). Even so, average number of fruits per branch did not differ between 2002 and 2003. Evidently flower production on a per-branch basis was high enough in 2002 to compensate for poor fruit set in that year, resulting in about as many fruits as in 2003.

Fire represents an important recruitment phase for many chaparral species. Prescribed burns are often scheduled during winter or spring when soil moisture is high in order to minimize risks of uncontrolled fire. However, chaparral wildfires typically occur in the summer or fall when soil moisture is low. Changing the seasonality of burn affects pre-burn soil moisture, burn temperature and timing of germination. High soil moisture during winter or spring burns is hypothesized to lower germination rates of chaparral plants compared to fall burns. The purpose of this study was to evaluate the effects of prescribed spring burns on the germination of chaparral species in the Mendocino National Forest, California. We conducted two experiments to test for effects of moisture on seed germination. In the soil heating experiment, soil collected under chaparral was heated at several temperatures and soil moistures, and germinating seeds were counted. In the seed heat treatment experiment, seeds of 13 species were heated moist and dry to determine the moisture effect on heated seeds. Results indicate a differential response of seeds to heat and soil moisture. Lotus humistratus, Daucus pusillus and Penstemon heterophyllus were negatively affected by temperature in both moist and dry treatments. Ceanothus cuneatus and Genista monspesullana germination increased with temperature in both dry and moist treatments. Germination of six species (Adenostoma fasciculatum, Camissonia contorta, Emmenanthe pendiflora, Epilobium ciliatum, Galium aparine and Malacothrix clevelandii) decreased under moist heat treatments. These results suggest that spring burns may lead to decreased diversity of chaparral due to reduced seed survival and germination of certain species.

The California chaparral community has a rich flora of species with different mechanisms for cuing germination to postfire conditions. Here we report further germination experiments that elucidate the response of several widespread shrub species whose germination response was not clear and include other species from the Sierra Nevada, which have not previously been included in germination studies. The shrubs Adenostoma fasciculatum and Eriodictyon crassifolium and the postfire annual Mentzelia dispersa exhibited highly significant germination in response to smoke treatments, with some enhanced germination in response to heating as well. The shrubs Fremontodendron californicum and Malacothamnus fremontii were stimulated only by heat-shock treatments. Seeds buried in the soil for one year exhibited substantially higher germination for controls and most treatments. In the case of two postfire annuals, Mimulus bolanderi and M. gracilipes, germination of fresh seed was significantly greater with smoke or heating but after soil storage, over two-thirds of the control seeds germinated and treatment effects were not significant. These two annuals are generally restricted to postfire conditions and it is suggested that control germination of soil-stored seed may be a light-response (which was not tested here) as previously reported for another chaparral species in that genus.

In fire-prone vegetation, non-sprouting, obligate-seeding species depend on a persistent seed bank to reestablish post-fire populations. Thus, for such seeds, seed development and survival in the soil are critical life history stages. The objectives of our study were to examine the structure and composition of Ceanothus seed banks, analyze the viability of seeds in the soil, and determine rates of predation before and after seed dispersal. This study focused on populations of Ceanothus jepsonii var. albiflorus (J. Howell), which is restricted to serpentine soils. We also included data on Ceanothus cuneatus (Hook.) Nutt., a widespread, non-restricted species, for comparison. We found that the seed bank of C. jepsonii loses seeds due to destruction or removal at several stages of development. Pre-dispersal seed predators attacked 37% of inflorescences included in experimentation and up to 50% of shrubs from which fruits were collected, post-dispersal predators removed over 70% of seeds in the litter. There was a 30% reduction in viability of older intact C. jepsonii seeds in the soil compared to seeds collected from plants during the study. A beetle in the genus Zabrotes, not previously known to oviposit on Ceanothus, was determined to be a causal agent of pre-dispersal seed predation, with other pre-dispersal predators and parasites also possible. These findings suggest that Ceanothus seed banks are quite dynamic and subject to a variety of seed losses during several stages prior to germination, which may ultimately be responsible for soil seed banks remaining relatively constant rather than building up over time.

In the 1920s and 1930s Albert Everett Wieslander and several others explored much of California's wilderness sampling vegetation, taking photographs, collecting specimens, and drawing detailed maps of what they found. The collection is now known as the Wieslander Vegetation Type Mapping (VTM) collection, and the entire survey encompassed nearly seventy million acres of the state, covering most of the wild areas exclusive of the deserts and the larger agricultural areas. These data represent a valuable resource for comparative and conservation ecology. We are digitizing the entire project, and making it available to researchers and the public. The current “VTM Digitization” Project, as it is known, is described in this article, and is a collaborative effort by teams at University of California Berkeley and University of California Davis, funded by the U.S. Forest Service and U.S. Department of Agriculture's Cooperative State Research, Education and Extension Service. The VTM Digitization Project aims to digitize the entire VTM collection for use in ecological and geospatial analyses, and to facilitate access and distribution of the data by researchers and interested parties. This article describes our efforts at making the VTM plot data, maps and photographs digital, spatially referenced, readily available, and web-accessible via an Internet-based Geographic Information System (webGIS) application. In addition, we discuss potential uses for the data and caveats associated with its use, particularly spatial accuracy.

Streptanthus vernalis is a newly described species inhabiting serpentine rock outcrops in the Three Peaks area in Lake County, California. Morphological and allozyme data indicate that this taxon is related to the S. morrisonii complex.

Meiotic and mitotic chromosome numbers for Mentzelia leucophylla Brandegee (Loasaceae) are reported. The numbers of n = 11 and 2n=22 fit with the aneuploid series that exists in other taxa of Mentzelia section Bartonia, but differ from a chromosome number of n = 18 reported in 1973 by Reveal & Styer. Although additional work should be done on the species, it is suggested that the 1973 count may be in error.