• Desert Plants, Volume 34, Numbers 1-2 (July 2018)

      Bertelsen, C. David; University of Arizona, School of Natural Resources & the Environment and Herbarium (University of Arizona (Tucson, AZ), 2018-07)
      Since 1984 I have recorded all flowering plant taxa along a five-mile canyon route that climbs 4158 ft (1267 m) to the summit of Mount Kimball in the Santa Catalina Mountains of southern Arizona. In this flora of vascular plants in the Finger Rock Canyon Watershed, I describe the study area and its six vegetative associations, then discuss the impacts of drought, non-native species, and fire. The annotated flora, primarily based on data collected through 2017, includes information on abundance, distribution, vegetative associations, elevation where found, and months and years blooming. To investigate the effect of elevation on species richness and flowering duration, I divided the trail into five segments, approximately one mile (1.6 km) in length, and have focused primarily on an area about 30 ft (9.1 m) on either side of the trail. The phenological data collected is summarized for each taxon seen flowering from 1984-2017. The flora currently includes 615 specific and infraspecific taxa in 363 genera and 84 families. Although the watershed includes only about 0.6% of the area of the Santa Catalina Mountains, approximately 45% of the known flora of the range has been found here. This is particularly remarkable considering the area I have surveyed on foot is only about 7% of the watershed and less than 0.06% of the entire range.
    • Desert Plants, Volume 33, Number 2 (January 2018)

      Verrier, James T.; University of Arizona Herbarium (University of Arizona (Tucson, AZ), 2018-01)
      The Santa Catalina Mountains are located in Pima and Pinal counties in southeastern Arizona. The study area is defined as approximately 259,000 acres (104,813 hectares) or 405 mi2 (1,048 km2), spanning an elevational gradient of 6,457 ft (1,968 m). Located on the northwestern edge of the Madrean-influenced sky island complex of southeastern Arizona and northern Sonora, highly diverse plant communities range from Sonoran Desert to subalpine forest. A total of 380 days of field work were conducted between 2007–2017, including extensive exploration of the remote east side of the mountains. The vascular flora includes 1,360 taxa in 127 families and is currently the largest of any range in southern Arizona. Non-native plants are represented by 167 taxa and comprise 12.3% of the total flora. The three largest plant families are Asteraceae, Poaceae and Fabaceae, with 213, 187 and 107 taxa respectively. Euphor-bia, Muhlenbergia and Dalea are the largest genera with 24, 22 and 16 species. A total of 375 taxa are found on lime-stone or dolomitic substrates. There are 69 historically collected taxa that have not been seen or collected in 55 years, which are excluded from this checklist. New additions to the vascular flora are vouchered at the University of Arizona Herbarium. A checklist of 169 non-vascular plants from 36 families, based on over 1,150 collections from 18 national herbaria, is included. The floristic diversity of this sky island represents nearly a third of the entire state flora, while occupying less than half a percent of the state’s area. Geographic location, elevational gradient, geological diversity, and a high percentage of species found at the edge of their ranges contribute to the rich diversity of this unique mountain range.Monsoon storms cover the west side of the range.
    • Name Changes for Legumes Used in Southwest Landscapes: Acacia, Caesalpinia, Lotus, and Sophora

      Johnson, Matthew B.; Univ Arizona (University of Arizona (Tucson, AZ), 2017-10)
    • THE DESERT EDGE: FLORA OF THE GUAYMAS REGION OF SONORA, MEXICO. PART 1: THE CHECKLIST

      Felger, Richard Stephen; Carnahan, Susan Davis; Sanchez-Escalante, Jose Jesus; Univ Arizona, Herbarium (University of Arizona (Tucson, AZ), 2017-10)
      A checklist is provided for the vascular plants of the Guaymas region of western Sonora. This region encompasses 532,000 hectares (1,314,600 acres) where the southern Sonoran Desert transitions from subtropical thornscrub. This flora includes 820 native and non-native taxa in 113 families and 471 genera. There are 97 non-natives established in the flora area, 27 of which are grasses. Nineteen taxa are endemic to the flora area.
    • Habitat Preference of Three Parasitic Orchids Occurring Sympatrically in an Arizona Sky Island

      Verrier, James T.; Univ Arizona, Sch Plant Sci (University of Arizona (Tucson, AZ), 2017-10)
      Detailed habitat information for the holomycotrophic orchids, Corallorhiza maculata, C. striata, and C. wisteriana, was recorded from multiple sites in the Santa Catalina Mountains, southeastern Arizona. This study was initiated to see if there are predictable associations with host trees. Over 1,400 flowering stems were observed from 244 microsites at 10 localities across a 305 m elevational gradient, and within an area of 7 km2 (700 hectares). While C. maculata showed a preference for southwestern white pine (Pinus strobiformis), C. striata associated with white fir (Abies concolor) and bigtooth maple (Acer grandidentatum). White fir and Douglas-fir (Pseudotsuga menzesii var. glauca) were the preferred associates of C. wisteriana. Orchids were found at microsites along lower slopes at up to 45% inclinations and generally 3-24 m above the slope base. Nearly all sites were north facing with moderate to thick leaf litter. A third of all microsites had no forbs or graminoids associated with orchid clusters, confirming the obligate association with primarily conifers. The local distribution showed a pattern of niche partitioning, with the three species occurring in similar habitats but depending on different host trees. Although C. striata and C. wisteriana associated mainly with white fir, C. striata favored habitat with more nutrient-rich soils.
    • A Mycoheterotrophic Orchid, Tomentelloid Fungi, and Drought in an Arizona Sky Island

      Verrier, James T.; Univ Arizona, Herbarium (University of Arizona (Tucson, AZ), 2017-10)
      A large population of the fully mycoheterotrophic orchid, Corallorhiza striata var. vreelandii, was monitored for nine years, 2009—2017, in the Santa Catalina Mountains of southeastern Arizona. High elevation slopes were chosen for an unusually high density of plants. Orchid stems were counted annually, and the number of flowering stems steadily decreased by 78% during the first seven years (2009–2015) in drought conditions. Following a partial return to average rainfall on the seventh through ninth years, the number of stems dramatically rebounded on the eighth and ninth years. Overall the total number of flowering stems decreased by 35% during the study. Precipitation from the previous winter and summer strongly correlated with the number of flowering stems observed. Years of extreme drought, with less than half of annual averages, resulted in a decline of flowering stems for two consecutive years, even when the following year had average rainfall. Two years of near average rainfall resulted in an increase on the second year. Orchid numbers were observed to fluctuate as its endophyte was dynamically affected by changes in annual precipitation. This study highlights the need for research on the impact of drought to ectomycorrhizal fungi and affiliated plant species.
    • Cultivation of Ocotillo from Seeds to Flowers: A Ten Year Experience in Northern Italy

      Ceotto, Enrico (University of Arizona (Tucson, AZ), 2017-10)
    • Desert Plants, Volume 32, Number 1 (September 2016)

      McAuliffe, Joseph R.; Desert Botanical Garden (University of Arizona (Tucson, AZ), 2016-09)
      Portions of the eastern Mojave Desert region of southeastern California, southern Nevada, and west-central Arizona that receive significant inputs of warm-season precipitation contain large areas dominated by various C4 perennial grasses including Pleuraphis rigida, P. jamesii, Bouteloua eriopoda, and B. gracilis. The lower elevation at which the two Bouteloua species occur rises from east to west in response to diminished precipitation, especially that received during the warm season. Unpredictability of warm-season precipitation also increases from east to west, but these grasses occasionally make use of cool-season precipitation stored in the soil, once temperatures required for the C4 photosynthetic pathway are achieved in late spring, but before the onset of summer monsoonal precipitation. Species distributions vary with elevation, with P. rigida occurring at lower elevations, B. eriopoda and P. jamesii at intermediate elevations, and B. gracilis at higher elevations. Composition of communities containing the latter three species is similar to grassland formations of the cool-temperate grasslands (grama-galleta steppe) of the Colorado Plateau region. Small, less predictable amounts of warm-season precipitation probably impose the greatest limitation to the diversity of C4 grasses in the eastern Mojave Desert region. However, due to warmer minimum winter temperatures, the woody plant and succulent floras associated with perennial grasses in the eastern Mojave region bear greater resemblance to those of the warm-temperate, semi-desert grasslands of west-central Arizona, southeastern Arizona, and the Sonoran and Mojave Deserts. The presence of these woody plant and succulents in perennial grass-dominated communities in the eastern Mojave Desert imparts a structural character similar to that of the warm-temperate semi-arid grasslands of southern Arizona. Although climate (particularly warm-season precipitation) is a first-order determinant of the occurrence of perennial C4 grasses in the eastern Mojave Desert region, geological characteristics that control soil formation and soil hydrological behavior strongly influence composition of communities. The common denominator of sites dominated by grasses is a soil with relatively thick, fine-grained soil horizons that are conducive to exploitation by relatively shallow, diffuse, fibrous root systems of those grasses. Such soils occur in diverse settings, ranging from relatively steep hillslopes underlain by bedrock to gently inclined alluvial fans. In rocky hillslope environments, these kinds of soils are associated with late Pleistocene colluvium deposits in which eolian dust accumulation is principally responsible for forming the thick, fine-grained horizons. Erosion of these soils on hillslopes contributes to hydrological conditions more conducive to taproot systems of woody plants that occupy deeper fractures and joints in bedrock. Similarly, erosional truncation of well-developed soils of alluvial fans and exposure of cemented, relatively impenetrable calcic horizons produce a shift in dominance by perennial grasses to woody plants. In many settings, the presence of relatively dense perennial grass cover plays an essential role in moderating surface flows and inhibiting erosion. Prior to Anglo-American settlement of the region in the late 1800s, occasional wildfires may have fostered dominance of perennial grasses in some of these areas. Since the 1890s, livestock ranching has significantly impacted perennial grass-dominated vegetation. Removal of livestock from portions of the region around 2000, coupled with years of abundant warm-season precipitation, in some cases combined with wildfire, has led to a resurgence of perennial grasses in some areas. Effective management and conservation of these areas require a comprehensive understanding of the composition, occurrence, and ecological functioning of these communities.
    • Desert Plants, Volume 31, Number 2 (February 2016)

      Johnson, Matthew B.; Boyce Thompson Arboretum, The University of Arizona (University of Arizona (Tucson, AZ), 2016-02)
    • Desert Plants, Volume 31, Number 1

      Johnson, Matthew B.; Feldman, William R. (University of Arizona (Tucson, AZ), 2015-10)
    • The Boyce Thompson Arboretum and Desert Legume Program Expedition to South Africa

      Johnson, Matthew B. (University of Arizona (Tucson, AZ), 2015-10)
    • The Monte and Chaco Regions of Argentina

      Johnson, Matthew B. (University of Arizona (Tucson, AZ), 2015-10)
    • Down Under The Boyce Thompson Arboretum and Desert Legume Program Expedition to Australia

      Johnson, Matthew B. (University of Arizona (Tucson, AZ), 2015-10)
    • A Day in the Syunt-Khasardagh Zapovednik of Turkmenistan

      Feldman, William R. (University of Arizona (Tucson, AZ), 2015-10)
    • Desert Plants, Volume 17, Number 1 (June 2001)

      University of Arizona (Tucson, AZ), 2015-05-20
    • Desert Plants, Volume 16, Number 1 (June 2000)

      University of Arizona (Tucson, AZ), 2015-05-20
    • Intriguing Chihuahuan Desert Yuccas in Cultivation

      Starr, Greg (University of Arizona (Tucson, AZ), 2015-05-20)
    • Name Changes of Legumes Used in Southwest Landscapes

      Johnson, Matthew B.; Desert Legume Program, The University of Arizona (University of Arizona (Tucson, AZ), 2015-05-20)
    • Desert Plants, Volume 15, Number 2 (December 1999)

      Mauz, Kathryn; Arid Land Resource Sciences (University of Arizona (Tucson, AZ), 2015-05-20)
    • Landscape Water Use in Phoenix, Arizona

      Martin, Chris A.; Urban Horticulture Ecology Research Laboratory, Department of Plant Biology, Arizona State University (University of Arizona (Tucson, AZ), 2015-05-20)