Desert Plants, Volume 33, Number 1 (October 2017)
ABOUT THE COLLECTION
Desert Plants is a unique botanical journal published by The University of Arizona for Boyce Thompson Southwestern Arboretum. This journal is devoted to encouraging the appreciation of indigenous and adapted arid land plants. Desert Plants publishes a variety of manuscripts intended for amateur and professional desert plant enthusiasts. A few of the diverse topics covered include desert horticulture, landscape architecture, desert ecology, and history. First published in 1979, Desert Plants is currently published biannually with issues in June and December.
Digital access to this material is made possible by the College of Agriculture and Life Sciences, Boyce Thompson Southwestern Arboretum, and the University Libraries at the University of Arizona.
Contact Desert Plants editorial staff at email@example.com.
THE DESERT EDGE: FLORA OF THE GUAYMAS REGION OF SONORA, MEXICO. PART 1: THE CHECKLISTA 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 IslandDetailed 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 IslandA 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.