Effects of prefire stand age, fire intensity, and hillslope position on postfire vegetation recovery during the first two postfire seasons were studied in two contrasting stands of mixed chaparral at San Diego State University's Sky Oaks Field Station (San Diego County, CA). One stand was approximately 60-years old and the other 12-years old when both burned in the July 2003 Coyote Fire. The two stands showed contrasting patterns of postfire community composition among different plant groups based on their modes of postfire regeneration. Fire intensity was significantly higher in the older stand. Increased fire intensity was positively correlated with establishment of seedlings of Ceanothus greggii var. perplexans (an obligate seeder), and negatively correlated with seedling abundance of Adenostoma fasciculatum (a facultative seeder). Hillslope position was also important in determining patterns of abundance, suggesting that soil erosion and deposition following fire may have a significant effect on postfire community recovery on these steep sites. Alternatively, prefire differences in the chaparral community that were correlated with hillslope position may account for these differences. The postfire herbaceous community in the first year was dominated by Phacelia brachyloba, a fire annual. Contrary to expectations, this species was found in greater abundance in the old stand than in the young. Fire annuals were largely absent from the community in the second year, and were replaced in abundance by a variety of opportunistic native and exotic annuals.

Experimental burns involving rare plants can provide important information for managers of those species. This study examined the response to prescribed fire of Ceanothus roderickii, a federally endangered chaparral species endemic to gabbro soils of the Pine Hill Formation in western El Dorado County, California. I conducted a laboratory study of germination cues, a field comparison of germination and survival on burned and unburned plots, and a comparison of seedling survival in burned plot subplots that were protected from vertebrate herbivores by wire exclosures. Seed germination was stimulated by heat (70° or 100° C) followed by a cold treatment. Burned plots contained 22-fold more seedlings than unburned plots, and seedling survival was significantly greater on burned plots. Exclosures significantly increased seedling survival on burned plots by 2 yr postfire. Plants on burned plots began to bloom and to branch layer (root at the nodes) by the sixth year postfire, with larger plants producing more fruits and being more likely to branch layer. I concluded that C. roderickii was similar to other species in the subgenus Cerastes in its obligate-seeding response to fire. However, its ability to branch layer enabled C. roderickii to increase plant density in burned plots, and thus continue postfire population recovery, long after fire-stimulated seedling establishment ceased. Branch layering by C. roderickii allows a postfire recovery pathway that is unique among species of obligate seeding Ceanothus studied to date.

We examined the effect of removing the staminode of the rare Blowout penstemon, Penstemon haydenii, on female reproductive success in a south-central Wyoming population. We found no significant difference in fruit set or in seeds per fruit between flowers with and without staminodes. The most frequent flower visitor, the megachilid bee, Osmia brevis, modified its behavior when visiting flowers without staminodes. In intact flowers, O. brevis collected pollen by straddling the staminode and rubbing its head and thorax across the anthers. In flowers without staminodes, O. brevis, appeared to compensate for the increased distance to the anthers from the corolla floor by simply stretching its legs to make contact with the anthers. The smaller, native generalist sweat bee (Dialictus pruinosus), which commonly collected pollen in intact flowers, appeared disoriented in flowers without staminodes, and frequently left without collecting pollen. Other taxa (e.g., bumblebees, Bombus spp., the masarid wasp Pseudomasaris vespoides), appeared unaffected and plied the flowers without incident. We speculate that the staminode of Blowout penstemon is intermittently vestigial: where O. brevis, bumblebees, and P. vespoides are common, the staminode is of little consequence; where D. pruinosus is the primary pollinator, the staminode is essential to sexual reproduction by the plant.

Intraspecific variation in blackbrush (Coleogyne ramosissima Torr.) seed imbibition was quantitatively investigated in the Mojave Desert. Blackbrush seeds were collected from six isolated mountain ranges, with each range sampled from one high-elevation (1550 m) and one low-elevation (1200 m) location for a total of 12 populations. Under laboratory experimental conditions, seed dry mass and initial seed moisture content did not differ significantly among the 12 populations. High-elevation source seeds imbibed significantly more water than low-elevation source seeds, and this was likely associated with habitat-specific selection. However, differences in full imbibition among seed collection sites at the identical elevation were not significant. Germination of field-collected seeds was similar, ranging from 87 to 93% among the 12 populations. Results of this study suggest that among six isolated mountain ranges in the Mojave Desert, blackbrush seed imbibition varies with elevation, but not with latitude.

Chromosomes in excess of the basic complement have been known for 100 years. Nevertheless, in most species the role of supernumerary or B chromosomes remains unknown or speculative. Here, I describe the frequency, distribution, and transmission to progeny of supernumerary chromosomes in two widely distributed western North American polyploid complexes. Meiotic analyses of microsporocytes found one to four supernumerary chromosomes in 14% of the 293 populations examined in Eriophyllum lanatum, and one, two, or six supernumeraries in 15% of the 133 populations examined in E. confertiflorum var. confertiflorum. Most supernumerary chromosomes were in the size range of A chromosomes, indistinguishable from As, and did not pair with them. Artificial hybridizations showed that the supernumerary chromosomes were transmitted by either parent. Populations with supernumerary chromosomes were nonrandomly distributed in both species. Intervarietal or interspecific hybridization may be responsible for some of their nonrandom distribution in E. lanatum. Supernumerary chromosomes may be involved in the dysploid chromosome numbers in Eriophyllum.

The genus Arctostaphylos consists mostly of chaparral shrubs known by the common name manzanita, and one of the widest ranging of these is A. glandulosa Eastw., distributed from Baja California to Oregon. Particularly in the southern half of its range it exhibits complex patterns of morphological variation that have long presented taxonomic challenges. Phenetic analysis of morphological traits from over 1400 individuals from throughout the range were used to examine intra- and inter-population patterns of variation. Multivariate ordination and hierarchical cluster analysis were used to determine phenetic patterns linked with ecological and geographical distributions. These analyses suggest the hypothesis that this species comprises two lineages with a common origin but divergent in the presence or absence of glandularity: A. glandulosa Eastw. subsp. glandulosa, characterized by branchlets with long glandular hairs, scabrous or pubescent leaves, and nascent inflorescences with mostly foliaceous bracts; and A. glandulosa Eastw. subsp. cushingiana (Eastw.) Keeley, Vasey and Parker comb. nov., with non-glandular tomentose branchlets, glabrate or pubescent leaves and either foliaceous or short deltoid bracts. Populations dominated by one or the other of these morphotypes occur throughout the range and tend to be separated by elevation or distance from the coast, although mixed populations occur where these taxa come together.

Two other glandular subspecies are named here. One is A. glandulosa Eastw. subsp. leucophylla Keeley, Vasey and Parker, subsp. nov., with intensely glaucous leaves and commonly with foliaceous bracts. A second glandular subspecies is A. glandulosa Eastw. subsp. atumescens Keeley, Vasey & Parker, subsp. nov., a narrowly distributed Baja California endemic similar to the nominate subspecies except that it lacks a basal burl and does not resprout after fire.

Of the non-glandular tomentose taxa, in addition to A. glandulosa subsp cushingiana, several others are also recognized. One is A. glandulosa Eastw. subsp. crassifolia (Jepson) Wells, a well established coastal San Diego endemic recognized by darker and thicker leaves and smaller and flatter fruits. Another is a newly described taxon A. glandulosa Eastw. subsp. erecta Keeley, Vasey & Parker, subsp. nov., an endemic to northern Baja California recognized by the erect nascent inflorescenses. Two others have glabrate leaves and highly reduced deltoid often marcescent bracts; A. glandulosa subsp. adamsii (Munz) Wells, which has intensely glaucous leaves and is distributed from interior Riverside Co. south, and A. glandulosa Eastw. subsp. gabrielensis (Wells) Keeley, Vasey and Parker comb. nov., which has bright lustrous green leaves and greater fusion of nutlets, and is distributed from the interior San Gabriel Mountains of Los Angeles Co. north to the Sierra Madre Mountains of Santa Barbara Co. All non-glandular plants with long setose or villous hairs are A. glandulosa Eastw. subsp. mollis (Adams) Wells. This taxon includes plants with foliaceous as well as reduced bracts and is distributed throughout the Transverse Ranges from Santa Barbara to San Bernardino counties, with some outlying populations further south. This taxon shows a marked tendency for reduced stomatal densities on the upper leaf surface in the westernmost populations. Although all of the A. glandulosa taxa described here are known from allopatric populations, inte

Morphological and geographic variation in two Lathyrus and two Vicia species complexes is reviewed. The following new combinations are proposed: Lathyrus nevadensis S. Wats. var. cusickii (S. Wats.) Broich comb. nov., Lathyrus lanszwertii Kellogg var. sandbergii (T. White) Broich comb. nov., Vicia ludoviciana Nutt. ex T. & G. var. leavenworthii (T. & G.) Broich comb. nov., and Vicia nigricans H. & A. var. gigantea (Hooker) Broich comb. nov.

A new combination, Deinandra peninsularis (Moran) B. G. Baldwin, comb. nov., is proposed for D. greeneana subsp. peninsularis of Baja California, Mexico, a taxon that does not belong within D. greeneana, based on recent molecular and cytogenetic work. New chromosome counts for D. peninsularis and D. streetsii and previously reported counts for the other 20 species of Deinandra indicate that all perennial or facultatively perennial taxa of the genus share the modal, and probably basal, chromosome number of 2n  =  12_II. A new chromosome count for another member of the tarweed tribe, Arnica mallotopus [≡ Mallotopus japonicus] (2n  =  19_II), in Arnicinae, strongly contrasts with an earlier (somatic) count for that species (2n  =  18), which is often treated in a different genus based in part on the previously reported chromosome number.

A natural hybrid, Prunus ×pugetensis A. L. Jacobson & Zika, is described as the cross between introduced Prunus avium (L.) L. of Eurasia, and indigenous P. emarginata (Douglas ex Hook.) Eaton of western North America. It is intermediate in morphology, differing from P. avium in its pubescence, more slender leaves, smaller flowers, and peduncled inflorescences. It can be separated from P. emarginata by its broader leaves with coarser teeth, larger flowers with weakly notched petals, and occasional umbellate inflorescences. Unlike the parents, more than 99% of the flowers eventually abort and it rarely produces fruit. Spontaneous hybrids have been found in the lowlands of western British Columbia, Washington, and Oregon.

Lectotypes are selected for Cerasus californica Greene, Cerasus emarginata Douglas ex Hook., Cerasus erecta C. Presl, Cerasus kelloggiana Greene, Cerasus mollis Douglas ex Hook., and Prunus corymbulosa Rydb.

A new species, Platanthera yosemitensis Colwell, Sheviak and P. Moore, from Mariposa County, California, is described and illustrated. Endemic to wet montane meadows between the main stem and the South Fork of the Merced River in Yosemite National Park, it is distinct from Platanthera stricta Lindl., P. sparsiflora (S. Wats.) Schlecter, and P. purpurascens (Rydb.) Sheviak & W. F. Jennings based on vegetative habit, floral morphology, color, and fragrance and pollination mechanics.

Streptanthus longisiliqus G. Clifton & R. Buck is described as a new species from Butte, Tehama, and Shasta counties in northeastern California. The new species is a short-lived perennial in subgenus Pleiocardia, informal group Cordati. Based on several morphological characters, S. longisiliqus appears to be most closely related to the montane southern California species S. bernardinus and S. campestris; it is geographically disjunct from those taxa by approximately 600 km. Streptanthus longisiliqus occurs in montane coniferous forest, often in localized openings, and sometimes in disturbed places.