Packera franciscana (Greene) W. A. Weber and A. Löve is endemic to treeline and alpine habitats of the San Francisco Peaks, Arizona, USA and was listed as a threatened species under the Endangered Species Act in 1983. Species abundance data are limited in scope, yet are critical for recovery of the species, especially in light of predictions of its future extinction due to climate change. This study defined baseline population densities along two transects which will allow the detection of future population trends. Packera franciscana ranged from 3529 to 3722 m elevation along the outer slope transect and densities were 4.18 and 2.74 ramets m⁻² in 2008 and 2009, respectively. The overall P. franciscana 2009 density estimate for both transects was 4.36 ramets m⁻² within its elevational range of occurrence, 3471–3722 m. The inner basin density was higher, 5.62 ramets m⁻², than the estimate for outer slopes, 2.89 ramets m⁻². The elevation of the 2009 population centroid for both transects was at 3586 (±10 SE) m with the inner basin centroid significantly lower than the outer slopes centroid: 3547 (±7 SE) m vs. 3638 (±7 SE) m, respectively. In mid-September, 6–9% of the P. franciscana ramets were flowering and/or fruiting in 2008–2009. These results and our estimate of >36,000 P. franciscana ramets in <2% of its range would suggest that the species is locally abundant, persisting and reproducing.

Peniocereus striatus (Brandegee) Buxb. (Cactaceae) is an endemic Sonoran Desert cactus that reaches its northern range limit in southwestern Arizona. One U.S. population occupies a small area of Organ Pipe Cactus National Monument near the U.S./Mexico international boundary, which has been monitored since 1939. An extensive survey conducted in 2002, covering 177 ha, resulted in the discovery of 88 new plants, in addition to the relocation of 57 plants found in previous surveys. Despite potential increases in population size and spatial distribution, mean plant height and number of basal stems has not significantly changed in recent years. Bud scars revealed that a majority of the population was sexually mature. Peniocereus striatus occurrence increased with decreasing slope, spanned every slope aspect, and was highest on rocky soils, but was noticeably low on west and northwest slopes and areas where severe land degradation had previously occurred. Over half of P. striatus plants were nursed by shrubs and subshrubs, while 40% occurred under leguminous trees. A severe frost in January 2002 top-killed 19% of the population, with the greatest damage in drainage bottoms. However, long-term (1944–2002) climate records show that there has been an overall increase in the number of frost free days in the region, which, coupled with land use change, has implications for the future health of this population.

Understanding the natural patterns of regeneration following human disturbance is essential for effective restoration and management of second-growth forests. Despite their unique ecological character, little is known about these patterns in Sequoia sempervirens (D. Don) Endl. (Coast Redwood) forests. We examined the composition and structure of naturally regenerating stands with 360 randomly located sample plots across a chronosequence of five replicated age-classes (18 to 127 yr) and three old-growth reference sites. Results indicate a progression of stand characteristics towards old-growth conditions, with several measures reaching old-growth equivalence within the timeframe of the chronosequence. Stand density, canopy cover, and species richness reached old-growth equivalence within 41–80 yr; Shannon-diversity reached old-growth equivalence between 80–100 yr; and the density of redwood seedlings and shrub cover reached old-growth equivalence between 100–130 yr. Basal area, herb cover, and the relative dominance of S. sempervirens progressed toward, but did not reach, old-growth equivalence. Size-class analysis indicated an increase in the density of large diameter trees, with no change in the density of smaller size-classes after forty yr. Coast redwood associated understory species were favored on the older sites with the cover of Calypso bulbosa (L.) Oakes, Trillium ovatum Pursh, and Viola sempervirens Greene reaching old-growth equivalence, while Iris douglasiana Herb., Tiarella trifoliate L., and Achlys triphylla (Sm.) DC. did not. No non-native species were recorded in stands older than 60 yr. We conclude that coast redwood forests are resilient to human disturbance, though some old-growth characteristics may require more than a century to develop.

The rediscovery of bearded popcorn flower, the last confirmed collection of which was in 1892, is documented. The species is endemic to Napa, Solano, and Yolo counties, California, where it grows in vernal pools, vernal swales, and other moist areas in grasslands. Associated species include wetland and upland grasses and forbs typically found in the vernal pool-grassland ecotone.

Recent field collections and surveys of herbarium specimens have raised concerns about species circumscriptions and recovered several morphologically distinct populations in Mentzelia section Bartonia (Loasaceae). From the Colorado Plateau, we name M. paradoxensis from Paradox and Gypsum valleys of western Colorado, which is closely related to M. marginata. We name M. holmgreniorum from northeastern Arizona and M. filifolia from the northern border region of Arizona and New Mexico, both of which share morphological similarities with M. lagarosa, M. laciniata, and M. conspicua. From north central New Mexico, we name M. sivinskii, which is most closely related to M. procera and M. integra. We describe three varieties of M. longiloba, including M. longiloba var. yavapaiensis, which is distributed throughout Arizona, M. longiloba var. pinacatensis, which is narrowly distributed in the Pinacate Desert of Sonora, Mexico, and the northern Chihuahuan Desert M. longiloba var. chihuahuaensis. We propose the new combinations M. lagarosa and M. procera to alleviate the polyphyly of M. pumila.

A newly recognized endemic species, Brodiaea matsonii, is described. This highly localized species is restricted to a single extended population along Sulphur Creek, in Redding, Shasta County, California. Brodiaea matsonii is a diploid species (n  =  6) closely related to the more widespread B. minor, a polyploid species (n  =  12, 24), from which it differs by the slightly smaller pink flowers and by its habitat parameters. Brodiaea matsonii grows from cracks and crevices in bedrock along an intermittent stream within foothill woodland.

Howellanthus (Constance) Walden and R. Patt. is recognized as a new genus, containing a single species H. dalesianus (J. T. Howell) Walden and R. Patt., based on morphological evidence. Howellanthus dalesianus (Boraginaceae) is a small perennial herb, endemic to northern California and restricted to ultramafic soils. The species was first collected in 1936 by Ella Dales Cantelow and Herbert Clair Cantelow, described by John Thomas Howell as Phacelia dalesiana J. T. Howell, and later placed in the monotypic Phacelia subg. Howellanthus by Lincoln Constance.