Stream-bank stabilization structures, or revetment, can impact riparian systems by confining watercourses to the point where natural functions are limited. Removal of existing revetment may have considerable impacts to stream-bank stability however. The effects of revetment and revetment removal on vegetation and stream-bank morphology were measured on three streams in forests dominated by Sequoia sempervirens (Coast Redwood) in northern California. Data were collected using randomly located transects on three treatments; “no-revetment,” “revetment-intact,” and “revetment removed.” Results were compared between treatments using ANOVA at a 0.05 level of significance. On all three sites, species richness, vegetation cover, and tree seedling density were found to be highest where no revetment existed compared to where revetment was intact. Stream depth and stream-bank slope were highest where revetment was intact. Recovery of vegetation following removal of revetment was more site specific being most pronounced where recovery time was greatest and stream-bank restoration efforts were highest.

Human expansion into the Mojave Desert is a significant threat to rare desert plants. While immediate habitat loss is often the greatest concern, rare plants situated near areas where soil surfaces experience frequent disturbance may be indirectly impacted when fine particulate dust accumulates on leaf surfaces. Remaining populations of the federally listed Astragalus jaegerianus (Lane Mountain milkvetch) occur on land open to expanding military activities and on adjacent public land with increasing recreational use. This study was initiated to determine whether dust accumulation could decrease the vigor and fitness of A. jaegerianus through reduced growth. Beginning in early May 2004, plants located on Bureau of Land Management (BLM) land were dusted bimonthly at canopy-level dust concentrations ranging from 0 to 32 g/m², and physiology and growth were monitored until late June when plants senesced. The maximum experimental dust level simulates dust concentrations of Mojave Desert perennials neighboring military activities at a nearby army training center. Average shoot growth declined with increasing dust accumulation, but seasonal net photosynthesis increased. Further investigation of plants grown in a greenhouse supported similar trends. This pattern of greater net photosynthesis with increasing dust accumulation may be explained by higher leaf temperatures of dusted individuals. Ambient dust deposition measured in traps near field plants (May 2004–July 2004) ranged from 0.04–0.17 g/m²/ d, which was well below the lowest level of dust on experimental plants (3.95 g/m²/d). With this low level of ambient deposition, we expect that A. jaegerianus plants in this population were not greatly affected by the dust they receive at the level of recreational use during the study.

Alkali meadow habitat—a groundwater dependent ecosystem—is rare in California, and its response to fire has not been documented. We sampled vegetation in this habitat across a pumping-induced depth-to-water (DTW) gradient immediately before, then eight weeks after, a summer wildfire. After the fire in the burned area, we documented vigorous re-growth of native perennial grasses in areas of shallow groundwater but no re-growth of shrubs. The dominant grass Sporobolus airoides flowered in the shallow end of the DTW gradient but never advanced beyond vegetative phenology (leaves) in the drawn-down end. DTW explained 77% of the grass cover variance in the post-fire burned area, and 87% and 94% of the grass cover variance in the pre-fire and post-fire unburned (control) areas, respectively. This suggests that post-fire re-growth was re-establishing a cover-DTW relationship already present before the fire. The principal short-term fire effect was the elimination of shrub cover due to apparent shrub mortality. Our study shows fire may be an effective management tool for regenerating alkali meadow in areas of shallow groundwater. However, in areas subject to long-term water table drawdowns we found negligible grass re-growth and increased vulnerability to erosion, suggesting fire may accelerate the process of type-conversion from meadow to xeric shrubland.

Arceuthobium rubrum (Viscaceae) is a distinctive species of dwarf mistletoe having red to reddish-brown plants and red, shiny fruits. It is primarily distributed in the Sierra Madre Occidental of Durango, Mexico, but in 1972 a population of A. rubrum was reported from Oaxaca, Mexico, more than 1000 km south of the nearest population in southern Durango. Initially, this population was classified as a disjunct population of A. rubrum, but in 1989 it was described as a new species: A. oaxacanum. However, our morphological measurements and observations of the phenology for plants from Durango and Oaxaca indicate these populations are morphologically similar and flower and disperse seed at approximately the same time, supporting the results of recent molecular analyses indicating that the Oaxacan populations represent disjunct populations of A. rubrum.

The writing of revised treatments for selected California Malvaceae for the upcoming second edition of the Jepson Manual and the Flora of North America series (volume 6) has made several nomenclatural changes and explanations necessary. New combinations are made here for taxa in Sidalcea, including Sidalcea asprella subsp. nana, Sidalcea calycosa subsp. rhizomata, Sidalcea celata, and Sidalcea sparsifolia. Several taxa previously included within Sidalcea malviflora have been removed from that species and re-interpreted, resulting in the resurrection and acceptance of the names Sidalcea asprella Greene and Sidalcea elegans Greene. Comments are presented here on the status of Hibiscus lasiocarpos and Lavatera vs. Malva in the California flora. At least one native species has been added to the flora, namely, Iliamna rivularis, though it may no longer occur in the state. Four species of Malvaceae have become naturalized or have been found as waifs in recent years and are added to the flora, namely, Anoda pentaschista, Lagunaria patersonia, Lavatera olbia, and Lavatera trimestris.

The names of two eastern North Pacific kelps (Phaeophyceae, Laminariales, Alariaceae) were inadvertently validated by Josephine Tilden on labels to specimens distributed in the exsiccata “American Algae”. Lectotypes for Lessonia littoralis and Pleurophycus gardneri, which concomitantly are the types of the names of the monospecific genera Lessoniopsis and Pleurophycus, respectively, are herein designated from among specimens housed in the Herbarium of the University of Minnesota, Tilden's home institution. Lessoniopsis ranges from Kodiak Island, Alaska, to the Big Sur coast of Monterey County, California, whereas Pleurophycus ranges from southeastern Alaska to Pt. Piedras Blancas, San Luis Obispo County, California. Molecular data suggest that both Lessoniopsis and Pleurophycus belong to the Alariaceae, a departure from their previous familial placements in the Lessoniaceae and Laminariaceae, respectively.

We describe Arceuthobium abietinum subspecies wiensii (Wiens' dwarf mistletoe, Viscaceae), a dwarf mistletoe that severely parasitizes red fir and Brewer spruce in northwestern California and southwestern Oregon. This classification is based on morphological and host range differences between white fir dwarf mistletoe (Arceuthobium abietinum f. sp. concoloris), red fir dwarf mistletoe (Arceuthobium abietinum f. sp. magnificae), and Wien's dwarf mistletoe. Male and female plants of Wiens' dwarf mistletoe were consistently smaller than those of both white fir and red fir dwarf mistletoes, whose plants were about the same size. The shoot color of Wiens' dwarf mistletoe was frequently green-brown or red-brown, while the shoot color of white fir and red fir dwarf mistletoes was typically yellow-green or yellow. Differences in host specificity also distinguish Wiens' dwarf mistletoe from white and red fir dwarf mistletoes.

Streptanthus oblanceolatus T. W. Nelson and J. P. Nelson is here described and illustrated. It is endemic to steep metavolcanic bluffs along the gorge of the Trinity River above its confluence with the New River, where three voucher specimens have been obtained.