• 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.
    • Habitat Relationships of Some Native Perennial Grasses in Southeastern Arizona

      Bock, Jane H.; Bock, Carl E.; University of Colorado, Boulder (University of Arizona (Tucson, AZ), 1986)
      Successful management and restoration of any ecosystem requires knowledge of the habitat requirements of its component species, as manifested under natural or near - natural conditions. We measured abundances of common grasses in relation to environmental variables on an undisturbed grassland and oak savannah preserve in southeastern Arizona. Major environmental gradients separating species were 1) slope angle and associated soil differences, 2) distance above wash bottoms or floodplains, and 3) slope compass orientation and amount of oak canopy. Blue Grama (Bouteloua gracilis) was the most widespread and abundant species overall, but it reached highest densities on level lowlands, where it was dominant along with Sacaton (Sporobolus wrightii) and Vine Mesquite (Panicum obtusum). Sideoats Grama (B. curtipendula) was the most abundant species on steep slopes above floodplains and washes, regardless of tree canopy or slope compass orientation. Level to gently rolling uplands were dominated by Blue Grama, Plains Lovegrass (Eragrostis intermedia ), and Wolftail (Lycurus phleoides). Plains Lovegrass in particular seems to be increasing on the study area compared to adjacent grazed sites. Steep and rocky uplands were dominated by Threeawns (Aristida spp.), Curly Mesquite (Hilaria belangeri ), and Sprucetop Grama (B. chondrosioides). These species generally are characteristic of poor sites, and they were more common on grazed lands than on our study area.
    • Herbaceous exotics in Arizona's Riparian Ecosystems

      Stromberg, Juliet C.; Chew, Matthew K.; Center for Environmental Studies, Arizona State University; Arizona State Parks (University of Arizona (Tucson, AZ), 1997-06)
    • High Biodiversity in Association with the Common Baobab Tree

      Hellekson, Lyndsay; The University of Arizona, School of Natural Resources (University of Arizona (Tucson, AZ), 2009-06)
    • Historical Background to Southwestern Ecological Studies

      Brown, David E.; Minckley, W. L.; Collins, James P.; Arizona Game and Fish Department; Department of Zoology, Arizona State University (University of Arizona (Tucson, AZ), 1982)
    • The History and Vegetation of Nombinnie and Round Hill Nature Reserve

      Milthorpe, Peter; NSW Agriculture (University of Arizona (Tucson, AZ), 1998-06)
    • History, Geology and Vegetation of Picketpost Mountain

      Crosswhite, Frank S.; Boyce Thompson Southwestern Arboretum (University of Arizona (Tucson, AZ), 1984)
    • History, Observations and Monitoring of Pediocactus peeblesianus var. fickeiseniae on the Arizona Strip

      Hughes, Lee; The Bureau of Land Management (University of Arizona (Tucson, AZ), 1996-06)
    • Hohokam Use of Desert Food Plants

      Gasser, Robert E.; Museum of Northern Arizona (University of Arizona (Tucson, AZ), 1982-06)
    • Honey Bees and Desert Plants

      Crosswhite, C. D. (University of Arizona (Tucson, AZ), 1984)
    • Horticultural Survivors of a Southwestern Arizona Ghost Town

      Robinson, D. Lowell; Dobrenz, Albert K.; Agronomy and Plant Genetics Department, University of Minnesota; Plant Sciences Department, University of Arizona (University of Arizona (Tucson, AZ), 1994-06)
    • How Does Our Agave Grow? Reproductive Biology of a Suspected Ancient Arizona Cultivar, Agave murpheyi Gibson

      Adams, Karen R.; Adams, Rex K.; Laboratory of Tree Ring Research, University of Arizona (University of Arizona (Tucson, AZ), 1998-12)
      More than one species of Agave may have been cultivated by ancient farmers in Arizona. The arguments for this include apparent range extensions, burned Agave parts in archaeological roasting features, archaeological sites with in situ agaves thought to be relics of past human management, and limited molecular evidence. The reproductive biology of a single Agave murpheyi Gibson, one of the suspected cultivated species, is documented here in detail. After nine years of growth in a residential backyard in Tucson, Arizona, a flowering stalk rapidly elongated to 4.73 m (15.5 ft) during both daytime and nighttime hours from January through May. Daily records kept for much of that time revealed the stalk averaged 4.69 cm (1.85 in) of growth per day. Maximum growth spurts correlated with both high daily temperature and mean daily temperature. Lateral branches, eventually totaling twenty-two, began developing during March in the upper portion of the flowering stalk. Over a period of five weeks from late May to late June, these lateral branches flowered with normal-looking flowers, attracted a variety of potential pollinators, but produced no mature fruit. Instead, by the summer monsoon season of July and August, the mother plant had produced 359 miniature agaves or bulbils in these upper side branches. The bulbils appeared to arise from enlargements of tissue in the vicinity of the former flowers. Without releasing on their own, these bulbils became water-stressed and had to be forcibly removed a year later. By this time they were quite variable in fresh weight and size. Once planted, they rehydrated and immediately began to grow. This single plant shares aspects of bulbil production with three Agave murpheyi plants observed by others.
    • How the Use of Mesquite Impacts Grass Availability, Wild Ass Sanctuary, India

      Sinha, Bitapi C.; Goyal, S. P.; Krauseman, Paul R.; Wildlife Institute of India; Wildlife Biology Program, University of Montana (University of Arizona (Tucson, AZ), 2009-12)
      We examined the impact of an exotic mesquite (Prosopis juliflora) on grass availability in the Wild Ass Sanctuary (WAS), Western India, which is the only habitat for the endangered Indian wild ass (Equus hemionus khur). These data are necessary for the management of endangered species in desert ecosystems where resources fluctuate widely. We collected information on the size of mesquite branches used by people for fuelwood and the impact of branches that were left on the ground on grass cover and biomass during 1989-1990. People preferred fuelwood branches of mesquite 5-15cm in diameter; the remaining thorny branches are left in the field, which reduces the availability of grass for foraging. Most grasses that grow under the discarded mesquite branches are protected whereas grasses without this protection are grazed. We correlated the percent grass cover with the number of twigs left on the ground (r = 0.74). Grasses protected due to the thorny branches leftover after mesquite collection, provide sources of seeds but reduce overall availability of forage leading to increased crop depredation by wild ass. Managing mesquite branches in WAS is important to provide more grazing areas for minimizing crop predation by wild
    • How to Photograph Desert Plants and Flowers

      West, Joanne (University of Arizona (Tucson, AZ), 2009-06)
    • Human Disturbance and Vegetation in Arizona's Chiricahua Mountains in 1902

      Bahre, Conrad J.; Department of Geography, University of California (University of Arizona (Tucson, AZ), 1995-12)
    • Hummingbirds as Pollinators of Flowers in the Red-Yellow Segment of the Color Spectrum, With Special Reference to Penstemon and the "Open Habitat"

      Crosswhite, Frank S.; Crosswhite, Carol D.; Boyce Thompson Southwestern Arboretum; Department of Plant Sciences, University of Arizona (University of Arizona (Tucson, AZ), 1982-01)
    • Hunting the Elusive Organ Pipe Cactus on San Esteban Island in the Gulf of California

      Bowen, Thomas; The Southwest Center, The University of Arizona (University of Arizona (Tucson, AZ), 2003-06)
    • The Hybrid Palo Verde 'Desert Museum': A New, Superior Tree for Desert Landscapes

      Dimmitt, Mark A.; Arizona-Sonora Desert Museum (University of Arizona (Tucson, AZ), 1987)
      A recently released complex hybrid palo verde is described which exhibits the best phenotypic traits of the three species in its parentage. 'Desert Museum' has inherited from Parkinsonia aculeata very rapid growth (up to 2.7 meters, nine feet, per year), sturdy, upright growth habit, and large, bright flowers borne over a long season. From Cercidium spp. it has inherited small leaves. Unlike any species of palo verde, the hybrid is completely unarmed. Preliminary evaluation indicates that 'Desert Museum' is a nearly ideal tree for cultivation in desert climates. It grows to a functional size of seven meters (20 feet) tall and wide in three to five years, after which time it can be maintained on little or no supplemental water. Its growth habit requires little or no pruning or staking. The litter from the small leaves is inconspicuous and readily blows away or decomposes. The tree is apparently resistant to indigenous pests and diseases. Availability is currently limited until a method for large scale propagation is developed.
    • Hydrophytic Plants in Arizona's Palustrine Landscapes

      Rodiek, Jon; School of Renewable Resources, University of Arizona (University of Arizona (Tucson, AZ), 1980)