Several molecular studies in the last 12 yr have made phylogenetic relationships among the nearly 50 species of Allium L. (Alliaceae) in California much better known than details of the plants' biology in the field. Allium jepsonii (Ownbey & Aase ex Traub) S. S. Denison & McNeal, a rare geophyte nearly endemic to Butte County, was studied in the field for 4 yr on a serpentine outcrop at 736 m elevation south of Paradise Lake, to document aspects of growth and reproduction. Plants flowered in late June and early July. Plant density, scape height and numbers of flowers (averaging 26) in the solitary umbels varied significantly through the years, with some variation in these traits related to cumulative rainfall. Each year many flower buds failed to reach anthesis and only 54% of the flowers that opened produced fruits. Bagged flowers produced significantly fewer fruits and seeds than unbagged. Common flower visitors each year included a beefly, Bombylius facialis. Seeds per plant varied by year, with the 4-yr average (200 fruits total) at only 14. Over the years 82% of the fruits made single seeds, with 17% making two and only 0.3% making three. Seeds planted in the field germinated in the winter, with seedlings completing first year growth by June. The cotyledon served as the only photosynthesizing leaf, and elongation of lower parts of the cotyledon pushed the developing bulb into the soil. First year bulbs averaged up to only 2.4 mm maximum diameter, were pearly white, and lacked the dark coats seen on bulbs of flowering individuals.

Orocopia Sage, Salvia greatae Brandegee (Lamiaceae), is an endemic shrub restricted to the Orocopia and Chocolate Mountains within the Colorado Desert of Riverside and Imperial Counties, California. Very little has been published on this species' demographics, distribution, range, ecology, or threats. Generally, habitat for S. greatae has been described as alluvial fans, slopes, and washes between 30–450 m elevation. Our study was designed to focus specifically on documenting threats and describing the demographic patterns of S. greatae populations, as well as establishing a set of baseline data for long-term monitoring. Our surveys, performed in fall and winter of 2019–2020, revealed patterns that differed from the previously documented distribution for this species; we found denser, more expansive populations, and lower mortality rates at even higher elevations, up to 1011 m on steep slopes and rugged terrain. Populations at mid-elevations, 200 to 500 m, had higher mortality rates than high elevation sites. For populations previously considered to be within ‘core habitat’ at elevations below 200 m and within bajadas and alluvial fans, we relocated very few of the populations recorded in the early 1900s, and observed high mortality within those that persisted. Over the gradient studied, we found that the condition of plants significantly increased with elevation, with the highest proportion of vigorous individuals found at higher elevations. Our data indicate that either this species is shifting to higher elevations, or the previously described habitat of S. greatae was biased toward the lower, easily accessible populations, and may have been composed of waifs, as opposed to stable upland populations. Declines noted in mid- and lower-elevation populations are consistent with the effects of drying due to anthropogenic climate change.

We report the second edition of Napa County's vegetation map using California's Manual of Vegetation classification system and aerial imagery from 2016. It covers 2053.54 km², increases polygon resolution by 23.8%, contains 35,244 polygons, and has 71 landcover types, 60 of which are dominated by natural vegetation. It has an overall error rate of 2.6%, includes canopy density measures for 24 vegetation types, and contains explicit measures of structures in the Wildland Urban Interface (WUI). We compared the new map to the one based on 1993 imagery to ask how effective Napa county's agricultural preservation and conservation regulations have been at preventing conversion of natural vegetation across the county and of agricultural lands within and beyond the county's Agricultural Preserve, established in 1968. We examined net change and change detected using a transition matrix, to seek concealed landcover conversion. The net change shows small increases in Agriculture and Urban extents. However, the transition matrix found substantial Urban expansion into Agriculture, 12.9 km² overall and 226.9 ha (2.24%) within the Agricultural Preserve; and 30 km² of agricultural expansion into natural vegetation, including 595 ha of high conservation-value oak woodlands. Due to increased map resolution in the 2016 map, we identified stands of natural vegetation (Oak Woodlands, Grassland, and Chaparral) in areas previously mapped as Agriculture and Urban, as well as Oak Woodlands in areas previously mapped as other vegetation types. Their inclusion in net measures of landcover change substantially obscures actual loss in natural vegetation types and agricultural lands. The net loss for Oak Woodlands is 191 ha, but the transition matrix identifies 782 ha converted to urban or agriculture, which suggests only moderate performance for the county's conservation measures. We also found rates of vegetation change in wildfire-burned areas three times higher than in unburned areas. Conversion of agricultural lands to urban was about 2.3% in the Agricultural Preserve, but 6.3% beyond, showing that county zoning slowed urban expansion. We found changes in spatial resolution and mapping details between vegetation map editions made net measures of landcover change inaccurate, and that transition matrix-analyses provided more accurate accounting and identification of mapping methods errors.

Historical photographs are windows into the past. By comparing historical and modern photographs we can measure change; but how do we find the original camera location to repeat a photograph? Historical, geographic, topographic, and other clues may be used, but we lack a numerical method suitable for any user to find the general location of a historical photograph. We derive a geometric method that can be applied in the field or prior. The method uses measurements of at least three points of reference (POR) in the historical photograph and corresponding geographic locations measured via a compass or on a map. rePhoto, an open-source R package that applies the method and outputs spatial KML files for use with Google Earth, is provided. The geometric method was tested on 20 photographs with known locations and validated by independent users. The effectiveness of the method varied among users, but overall predicted a search area containing the original camera location 70% of the time (the prediction accuracy) and typically predicted search areas 99.5% smaller than the total region evaluated by the method. The method was robust regardless of whether three or four POR were used, and worked well even when POR were more than 30 km away. The proposed method only works for photographs with at least three identifiable geographic POR, thus other methods are illustrated for use more generally. California and the western USA have numerous iconic historical photographs, for which many locations could be found and re-photographed using methods described here.

An inventory of the vascular plants of Heil Valley Ranch and Hall Ranch in the north foothills of Boulder County was completed during 2017 and 2018, prior to a catastrophic forest fire that severely impacted this area in the fall of 2020. Heil Valley Ranch and Hall Ranch are keystone units of the Boulder County Parks and Open Space system. These large parcels (∼10,000 acres/4047 ha) represent a significant portion of publicly accessible open space in the county and represent an exemplary legacy of land preservation in the region. The biologically diverse foothill landscapes represent the ecotone between the High Plains and the Southern Rocky Mountains. Vital transition zones in the area harbor globally vulnerable and critically imperiled plant associations, the most detailed categorization described by the US National Vegetation Classification (2021). A total of 607 botanical specimens were collected over the course of 39 separate visits. There are 381 species from 82 families of flowering plants represented at the study area, with the greatest diversity occurring in Poaceae and the Asteraceae. Of these, 319 are native, 62 are non-native, and 7 species are of conservation concern. The present study is the first floristic study of these parcels and provides baseline data for future work in the area, as well as information for comparison to floristic works in the broader Front Range foothills region. Together, these studies inform conservation policy at a time when biodiversity is threatened both globally and locally. As the Front Range megaregion rapidly expands in human population, biological inventories will provide critical data to promote the expansion of conservation areas in parallel with urban growth.

A species of the diverse genus Senecio (Asteraceae), originally identified as the Australian S. quadridentatus Labill. and reported naturalized in Orange and San Diego counties, California, was determined to be correctly identified as the South African Senecio angustifolius (Thunb.) Willd. True Senecio quadridentatus is confirmed to be naturalized in southern California in Santa Barbara County, both in mainland coastal regions and on Santa Rosa Island. The two species differ in plant habit (perennial herb in S. quadridentatus, shrub in S. angustifolius), leaf length (60–130 mm in S. quadridentatus, 10–35 mm in S. angustifolius), head type (disciform in S. quadridentatus, discoid in S. angustifolius), and head shape and size (involucre narrowly cylindric and 6.5–10 mm in S. quadridentatus, involucre widely cylindric and 5–6 mm in S. angustifolius). Evidence for these determinations, a description for Senecio angustifolius, and a revision to the key to Senecio in California are presented. The eradication of these exotics in natural habitats of southern California is ongoing, but further monitoring is required.