• 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.
    • 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)
    • 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.
    • Cultivation of Ocotillo from Seeds to Flowers: A Ten Year Experience in Northern Italy

      Ceotto, Enrico (University of Arizona (Tucson, AZ), 2017-10)
    • 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.