Fire has become more extensive in recent decades in southwestern United States arid lands. Burned areas pose management challenges and opportunities, and increasing our understanding of post-fire plant colonization may assist management decision-making. We examined plant communities, soils, and soil seed banks two years after the 2005 Loop Fire, located in a creosote-blackbrush community in Red Rock Canyon National Conservation Area in southern Nevada's Mojave Desert. Based on a spring sampling of 20, 0.01-ha plots, live dead cover of the exotic annual Bromus rubens averaged nine times lower on the burn than on a paired unburned area. Perennial species composition shifted from dominance by late-successional native shrubs (e.g., Coleogyne ramosissima) on the unburned area, to dominance by native perennial forbs (e.g., Sphaeralcea ambigua, Baileya multiradiata) on the burn. Species richness of live plants averaged 26% (100 m² scale) and 239% (1 m² scale) greater on the burn compared to the unburned area. Only 5% of Larrea tridentata individuals resprouted, compared to 64% of Yucca schidigera and baccata. Fire and microsite (interspace, below L. tridentata, or below Yucca) interacted to affect several 0–5 cm soil properties, with higher pH, conductivity, and total P and K on burned Yucca microsites. Bromus rubens density in 0–5 cm soil seed banks was four times lower on the burn, and its distribution among microsites reversed. Below-shrub microsites contained the most B. rubens seeds on the unburned area, but the least on the burned area. Intense fire below shrubs may have increased seed mortality, an idea supported by >3-fold decreases we found in emergence density after heating seed bank samples to 100°C. Our study occurred after a post-fire period of below-average precipitation, underscoring a need for longer term monitoring that characterizes moister years.

I investigated the individual and joint effects of simulated herbivory and interspecific competition on survival of Coleogyne ramosissima Torr. (blackbrush) seedlings. Seeds of C. ramosissima and Bromus rubens L. (red brome grass) were collected at mid-elevations (1220 to 1770 m) of the Spring Mountains in southern Nevada. A pot trial experiment was conducted for six months (27 wk) in a controlled environmental greenhouse. This trial experiment, consisting of a 2 × 2 factorial design with simulated rodent herbivory and interspecific competition with B. rubens as the main effects, resulted in four treatments. Herbivory on C. ramosissima by heteromyid and non-heteromyid species of rodents was simulated by clipping the top 3 cm of young shoots. Significant interaction was detected between herbivory and competition for C. ramosissima seedling survival. When herbivory and competition were examined independently, both factors had significant adverse effects on C. ramosissima seedling survival, with the former having greater negative effect than the latter. Results of this study suggest that simulated rodent herbivory and B. rubens competition limited survival independently, and that a combination of herbivory and competition caused synergistic reductions in C. ramosissima seedling survival. Understanding the role of herbivory and plant competition in reducing survivorship of seedlings is crucial to the management and regeneration of C. ramosissima shrublands in the Mojave Desert.

In the 150 years since their introduction to the state, species in the genus Eucalyptus have become the most common non-native trees in California. A clearer understanding of the ability of different species to reproduce in the state is important for how we monitor the ecological impact of these abundant non-native trees and for predicting possible future invasions. Here we present current data on the diversity of Eucalyptus in California, which species are spontaneously reproducing, or have the potential to do so, where they can be found, how they can be identified, and our analysis, based on herbarium and field observations, of the potential ecological impacts of various species in the locations where they have been introduced. We also present a new dichotomous identification key, and botanical drawings of all naturalized species. We discuss the degree to which factors such as life history traits, commonness of planting, and native range influence reproductive behaviors of different species.

The nuclear ribosomal internal transcribed spacer and chloroplast rbcL-accD intergenic spacer regions of species in the Pungentes subsection of Chorizanthe (spineflower) were analyzed. The goals of the study were to ascertain the phylogenetic relationships of taxa in the C. pungens-C. robusta complex to each other and to the other Pungentes species. The ITS phylogenies showed that C. diffusa was most distant from the other species and that C. cuspidata, C. pungens and C. robusta were not monophyletic. The four varieties of the C. pungens-C. robusta complex resolved into montane and coastal groups but the groupings were not in agreement with current classification. Statistical parsimony analysis divided 26 chloroplast DNA haplotypes into four groups with the 18 sampled populations of the C. pungens-C. robusta complex displaying a high degree of phylogeographic structure despite some incomplete lineage sorting. The haplotype analysis was not discordant with the ITS phylogeny. Possible taxonomic revisions and implications for conservation and management are discussed.

The Emerald Lake Basin forms a subalpine watershed in the upper drainage of the Marble Fork of the Kaweah River in Sequoia National Park. The basin is 120 ha in area and covers an elevational range from 2804 m at Emerald Lake to 3416 m at the summit of Alta Peak. The flora of the basin includes 202 vascular plant species, distributed into 132 genera and 41 families, with the Asteraceae (25 species) and Poaceae (23 species) as the largest families. Herbaceous perennials make up about three-fourths of the flora, but unlike alpine habitats many of these are relatively tall upright species, particularly in wet habitats. The woody plant flora includes five tree species, all conifers, with Pinus monticola as the dominant. There are 19 species of woody shrubs present, including six evergreen and 13 winter deciduous species. Eight plant habitat types were delineated on the basis of geomorphic position related to soil conditions and water availability that influence species composition (Billings 1974). These were subalpine conifer forest, willow thicket, wet meadows, moist rock crevices, dry meadows, dry rock crevices, colluvium, and fellfields.

A federal survey of Rancho Muscupiabe in 1867 provided legal land description of 12,204 ha (30,145 acres) in San Bernardino Valley, southern California, which fortuitously includes records of prominent native vegetation marking the location of survey stations along the land grant boundary. We matched legal land descriptions to the mapped vegetation occurrences, documented before agricultural land use and urbanization cleared the land, to relocate site-specific species localities in 1867 for comparison to historical botanical collections and extant distributions. We show that Juniperus californica, a desert conifer uncommon in cismontane regions of southern California, occurred at Del Rosa near Little Sand Creek on the northern boundary of Rancho Muscupiabe, which extends the historical species range from nearest extant occurrences on alluvial terraces along the Santa Ana River Wash (7 km SE) and Cajon Creek (13 km W). Vegetation records accompanying the 1867 survey also document the endemic Juglans californica at Devil Canyon in the San Bernardino Mountains, and at the SE base of San Sevaine Ridge in the San Gabriel Mountains. The 1867 survey map predates earliest recorded botanical collections in San Bernardino County of Juniperus californica (JEPS48231) and Juglans californica (POM123336) by 15 yr. A synthesis of historical and modern data is presented to build upon comprehensive atlases of California vegetation and show that the easternmost distribution of Juglans californica extends along the cismontane foothills of the San Bernardino Mountains to Millard Canyon near Banning Pass.

Phacelia cicutaria Greene var. hubbyi (J. F. Macbr.) J. T. Howell warrants elevation from varietal to species status based on morphological evidence. It is distinguished morphologically from P. cicutaria var. cicutaria and P. cicutaria var. hispida (A. Gray) J. T. Howell by its more robust habit, more densely congested inflorescences, lack of mottled markings on the corolla, longer stamens and style, thick shaggy hairs on the stems and leaves, and calyx lobes that closely invest the fruit.

A new combination, Trifolium variegatum var. geminiflorum is proposed, and a key is provided for varieties of T. variegatum.