This study compares postfire regeneration and diversity patterns in fire-prone chaparral shrublands from mediterranean (California) and non-mediterranean-type climates (Arizona). Vegetation sampling was conducted in tenth hectare plots with nested subplots for the first two years after fire. Floras in the two regions were compared with Jaccard's Index and importance of families and genera compared with dominance-diversity curves. Although there were 44 families in common between the two regions, the dominant families differed; Poaceae and Fabaceae in Arizona and Hydrophyllaceae and Rosaceae in California. Dominance diversity curves indicated in the first year a more equable distribution of families in Arizona than in California. Woody plants were much more dominant in the mediterranean climate and herbaceous plants more dominant in the bimodal rainfall climate. Species diversity was comparable in both regions at the lowest spatial scales but not at the tenth hectare scale. Due to the double growing season in the non-mediterranean region, the diversity for the first year comprised two different herbaceous floras in the fall and spring growing seasons. The Mediterranean climate in California, in contrast, had only a spring growing season and thus the total diversity for the first year was significantly greater in Arizona than in California for both annuals and herbaceous perennials. Chaparral in these two climate regimes share many dominant shrub species but the postfire communities are very different. Arizona chaparral has both a spring and fall growing season and these produce two very different postfire floras. When combined, the total annual diversity was substantially greater in Arizona chaparral.

Morphological and isoenzyme variation among populations of western azalea, Rhododendron occidentale (Torr. & A. Gray) A. Gray, were examined. Three regional parapatric groups were revealed: 1) the northern California outer North Coast Ranges; 2) the northern California and southern Oregon Klamath Ranges; and 3) the central California Sierra Nevada and southern California Peninsular Ranges. A highly variable but generally intermediate fourth group is restricted to ultrabasic substrates (serpentine) in the middle and inner North Coast Ranges of California. It is comprised of populations with recombined morphologies and alleles that were otherwise restricted to one or more of the three groups above. A revised intraspecific treatment is proposed, with the three regional groups above recognized as varieties. These are: R. occidentale (Torr. & A. Gray) A. Gray var. occidentale (outer North Coast Ranges), R. o. var. paludosum Jeps. (Klamath Ranges), and Rhododendron. occidentale var. californicum (Torr. & A. Gray) Hrusa comb. et stat. nov. (Sierra Nevada and Peninsular Ranges). Lectotypifications of Azalea occidentalis Torr. & A. Gray isotypes at PH and GH, Azalea californica Torr. & A. Gray in Durand, and Rhododendron sonomense Greene (NDG) are also provided.

The presence of autocorrelation invalidates all standard statistical tests unless special corrections are made. Because of this, it is important to know the degree of spatial autocorrelation in order to know how to sample. Mountain meadows were sampled to determine spatial autocorrelation of vegetation at the plant community level. A total of 40 meadows were sampled in the eastern Sierra Nevada, California. At each meadow a dominant plant community was selected for sampling. Sampling consisted of placing 10 × 10 cm quadrats at 1-m intervals on a 20-m transect and recording the presence for all vascular plant species rooted in the quadrats. Sites varied in plant species composition and number of species present. For each plot, ordination analysis in the form of reciprocal averaging was used to derive positions for each quadrat on axis 1. The scores from axis 1 were analyzed by semivariance to obtain the spatial dependence of the quadrats. Overall, three semivariance patterns were seen; A) plant communities that were autocorrelated at distances of less than one meter; B) communities that were autocorrelated between 1 m and 15 m; C) communities that were autocorrelated at distances greater than 20 m. Results indicate that for semivariogram type B, on average, sites were autocorrelated to a distance of 3.6 m, meaning that quadrats separated by greater than 3.6 m were independent. Beta diversity was significantly (P < 0.05) lower for semivariance type C than for either semivariance types A or B. These results are useful for determining spacing of sample points in mountain meadows to ensure spatial and statistical independence for presence/absence data.

Eriogonum evanidum Reveal is an annual herb in the buckwheat family that is endemic to southern California, USA and northern Baja California, Mexico. It was described by James Reveal in 2004 and was determined to be extinct due to the lack of recent observations and accessioned specimen collections. During field surveys conducted in 2007 and 2008 this species was rediscovered across its known range in southern California. Three of 10 historic occurrences that were presumed extirpated were located. One new occurrence was documented in the vicinity of Holcomb Valley, San Bernardino Mountains, CA. Location and habitat information are provided and the current conservation status of this species is discussed.

Ptychostomum pacificum J. R. Spence & Shevock, a new and highly distinctive species restricted to fen habitats within coniferous forests in California, Oregon, and extreme western Nevada is described and illustrated. This species appears to be related to P. turbinatum (Hedw.) J. R. Spence but is easily distinguished by a combination of features including large size, percurrent yellowish-brown costa with numerous incrassate cells at the leaf tip, strongly recurved leaf margins, and elongate cylindrical to narrowly pyriform capsules.

In preparing the treatment for Polemoniaceae for the Flora North America North of Mexico it is necessary to propose a new combination in Linanthus (Polemoniaceae).