• Observations and Comments on Pediocactus sileri in Arizona and Utah

      Gierisch, Ralph K.; Arizona Strip District, U.S.D.I. Bureau of Land Management (University of Arizona (Tucson, AZ), 1981)
    • Observations on Seeds and Seedlings of Fremont Cottonwood

      Fenner, Pattie; Brady, Ward W.; Patton, David R.; Arizona State University; Rocky Mountain Forest and Range Experiment Station, USDA Forest Service (University of Arizona (Tucson, AZ), 1984)
    • Observations on Some Chihuahuan Desert Yuccas

      Johnson, Matthew B.; The University of Arizona, Desert Legume Program (University of Arizona (Tucson, AZ), 2015-05-20)
    • The Occurrence of the Desert Fan Palm, Washingtonia filifera, in Southern Nevada

      Cornett, James W.; Palm Springs Desert Museum (University of Arizona (Tucson, AZ), 1988)
    • Oman Botanic Garden: A Unique Desert Botanic Garden in the Making

      Oliver, Ian B. (University of Arizona (Tucson, AZ), 2014)
      The Sultanate of Oman is an old sea-faring country located in southeastern Arabia. The coastline of Oman is approximately 1750 km long. It extends from the Musandam peninsula in the north of the country, which includes the important sea-lane of the Straits of Hormuz, to the border with Yemen in the south. Neighboring countries are the United Arab Emirates to the north, Saudi Arabia to the west and Yemen to the south. The Sultanate has a free market economy. Oil and gas are its biggest drivers. However, because of the realization that the oil reserves will not last forever, one of the initiatives is to capitalize on tourism. Scenically, Oman is an extremely beautiful country; it offers everything from pristine beaches and fascinating rugged mountains where terraced agriculture is practiced very successfully, to rolling red desert sands that stretch as far as the eye can see. Then, in the south, there is the unique escarpment of the southern mountains of Dhofar, whose seasonal mists attract vast numbers of tourists in the height of the season every year. In 2012 Oman was voted one of the world’s top tourist destinations. It is a country where one can still see the real Arabia without too much glitz and glamour. The best time to enjoy its unique beauty and attractions is from November through mid- April. These are the coolest months of the year. Climatically, Oman is a hot country. Typically summers along the coastline and in Muscat can reach a maximum of 48°C and may be unbearably humid during the months of August and September. Inland temperatures may exceed 51°C. The higher mountainous areas can reach 32°C in summer. Winters, which are generally from late November till mid-March, are cool and mild with rain falling mainly in January. Maximum winter temperatures in Muscat do not normally exceed 25°C and the minimum temperature is around 8°C. The higher Hajar mountains (2800 m - 3000 m) experience freezes (-3°C) and occasionally receive light snow in mid-winter. The annual rainfall in Muscat is approximately 120 mm. Tropical cyclones are rare but in recent years have caused severe damage along the coast and inland as well - for example, Cyclone Gonu in June 2007. The Oman Botanic Garden project was promulgated by Royal Decree in 2006. The GPS coordinates for the garden are North 23° 33’ 35.65’’ and East 58° 07’ 50.95’’. The garden is a first for Oman and for the Gulf region as a whole, as it will focus almost entirely on the native flora of this country alone. The Oman Botanic Garden nursery is tasked with growing all the plants needed for this massive undertaking. In addition to native Omani plants, the plants of the ancient agricultural terraces will also be cultivated and displayed: Damascus roses, citrus, deciduous stone fruits, pomegranates and date palms. Most of the deciduous fruit trees and roses grown in Oman are cultivated on the cooler mountain terraces and irrigated using the ancient falaj (water canal) system. Some of these working falaj systems are hundreds of years old—the canals are constructed of stone and mortar. The more modern falaj are built of block and cement. All falaj work on gravity and the keeper of the canal ensures that equal amounts of water are allocated on a daily basis to those who own plots on the agricultural terraces. The garden is situated northwest of the capital city, Muscat, on 420 ha of nature reserve. It is within easy reach of the international airport (20 minutes) and the main Sultan Qaboos Harbor (45 minutes). Arid, undulating topography, interspersed with seasonal wadi systems (intermittent streams), is fairly common on the Oman Botanic Garden site. Lower hill slopes are covered mainly in Acacia tortilis. To the south and west, one can make out the Western Hajar mountain system.
    • On the Cenozoic Ecology and Evolution of the Sahuaro

      Lowe, Charles H.; Steenbergh, Warren F.; Department of Ecology and Evolutionary Biology, University of Arizona (University of Arizona (Tucson, AZ), 1981)
      A 3-year field experiment (1976 through 1978) was conducted at Yuma, Arizona and Logan, Utah to determine the effects of environment on growth and grain yield of Siete Cerros and Cajeme 71 wheat (Triticum aestivum L.) geotypes grown under irrigation. The growing seasons were December to June in Arizona and April to August in Utah. Siete Cerros produced taller plants and higher straw and grain yields than did Cajeme 71; however, Cajeme 71 required fewer days from planting to flowering and flowering to maturity, at each location each year. Cultivars grown in Arizona produced taller plants, more straw, and more grain than the same cultivars grown in Utah; however, both cultivars required more days from planting to flowering and fewer days from flowering to maturity in Arizona than they did in Utah. Some plant growth characteristics of both cultivars varied from year to year but the variations were not consistent enough to suggest genetic differences between cultivars, except for plant height. This foregoing research suggested that a 3-year period was not long enough to indicate genotype-environment interactions; however, it may be safe to conclude that spring wheat cultivars may quickly adapt into high yielding winter annuals in irrigated, semiarid regions like Arizona. Additional Index Words. Genotypes, Varieties, Plant Adaptation, Plant Culture.
    • On the Pollen Harvest by the Honey Bee (Apis mellifera L.) Near Tucson, Arizona (1976-1981)

      O'Neal, Robert J.; Waller, Gordon D.; U.S.D.A. Agricultural Research Service, Carl Hayden Bee Research Center (University of Arizona (Tucson, AZ), 1984)
    • The Outdoor Classroom Program at the Boyce Thompson Southwestern Arboretum

      Crosswhite, Carol D. (University of Arizona (Tucson, AZ), 1983)
    • The Outstanding Stamens of Pennisetum clandestinum

      Mauz, Kathryn; University of Arizona Herbarium (University of Arizona (Tucson, AZ), 2007-06)
    • The Page Ranch Story - Its Vegetative History and Management Implications

      Schmutz, Ervin M.; Sourabie, Martin K.; Smith, David A.; School of Renewable Resources, University of Arizona; Bobo; U.S.D.A. Soil Conservation Service (University of Arizona (Tucson, AZ), 1985)
    • Patterns on Desert Plants

      Newell, Alan C.; Shipman, Patrick D.; Cooke, Todd J.; Department of Mathematics, The University of Arizona; Department of Mathematics, Colorado State University; Department of Cell Biology and Molecular Genetics, University of Maryland (University of Arizona (Tucson, AZ), 2012-06)
      The patterns seen in both the phyllotaxis and surface morphologies in the vicinity of the shoot apical meristems of plants are discussed. We begin with many pictures and a narrative descriptive of both the universal and anomalous features of desert and other plants. We then briefly outline explanations and open challenges. Although many of the special features of phyllotaxis have been known for over four centuries, only now are mechanistic explanations beginning to emerge.
    • Perennial Festuca (Gramineae) of New Mexico

      Allred, Kelly W.; Rance Science Herbarium (NMCR), Department of Animal & Rance Sciences, New Mexico State University (University of Arizona (Tucson, AZ), 2005-12)
    • Phenology and Stand Composition of Woody Riparian Plants in the Southwestern United States

      Brock, John H.; School of Agribusiness and Environmental Resources, Arizona State University (University of Arizona (Tucson, AZ), 1994-06)
      Knowledge of phenology is important for understanding the autecology of a species. Information concerning flowering dates, leaf development, seed/fruit dispersal, and aberrant weather effects on phenological status of a species should be well utilized by persons interested in the ecology, management and restoration of riparian communities. The phenology and stand composition of key woody species from selected riparian areas of the southwestern United States was studied. Eight riparian tree species were observed monthly (bimonthly in summer) at six sites in eastern Arizona and New Mexico. Phenological events were placed into eight categories for data collection. Stand composition data was collected from four randomly located macroplots at each site in the summer of 1983. Weather data for the period of study was summarized for the region. Four general phenology groups were identified: 1) spring flowering and fruit dispersal as characterized by Fremont cottonwood (Populus fremontii) and Goodding willow (Salix gooddingii), 2) Spring flowering/autumn-winter fruit dispersal characterized by box elder (Acer negundo var. interius), netleaf hackberry (Celtis reticulata), Arizona sycamore (Plantanus wrightii), and velvet ash (Fraxinuspennsylvanica ssp. velutina), 3) Spring flowering and late summer fruit dispersal demonstrated by Arizona walnut (Juglans major), and 4) Multidate flowering and fruit dispersal displayed by velvet mesquite (Prosopis velutina). Fremont cottonwood and Goodding willow dominated the sites, while netleaf hackberry, box elder, velvet ash and Arizona walnut were minor components of the stands. Variation in phenology of the tree species reflected individual species adaptations to the particular environment.
    • Phenotypic Variations in Communities of Calligonum comosum L'Her (Polygonaceae) from Saudi Arabia

      Taia, Wafaa K.; Moussa, Sanaa A. I.; Alexandria University, Botany Department; Cairo University, Botany Department (University of Arizona (Tucson, AZ), 2011-12)
      Vegetative community structures and phenotypic variations within Calligonum comosum L'Her communities growing in two different locations in Saudi Arabia, Nefud Al-Shakika and Al-Dahnaa, have been studied. Eleven species have been recorded in both areas; five of them were present in both locations. Ephedra elata and Convolvulus lanatus were recorded in Nefud Al-Shakika only, while Heliotropium bacciferum, Cleome arabica, Dodonaea vis cos a and Erodium gleurocophyllum were found in Al-Dahnaa only. The Importance Values of the species recorded have been calculated and cluster analyses of the studied quadrats have been conducted using TWINSPAN. Vegetative morphological characteristics showed great variation within Calligonum comosum collected from the two locations. Floral morphological characteristics were more stable, except for fruit color and hair which were different in the Calligonum comosum plants grown in the two locations. Epidermal stem secretions as well as mineral content varied in response to change in location. AN OVA tests have been carried out to evaluate the differences between the two areas. The variations in these characteristics are discussed according to the differences in climate, soil and water availability.
    • Physiological and Stuctural Mechanisms of Niche Differentiation for Three Sky Island Oaks in Relation to Light and Temperature

      Poulos, Helen M.; Berlyn, Graeme P.; Goodale, Uromi M.; School of Forestry and Environmental Studies, Yale University (University of Arizona (Tucson, AZ), 2008-06)
      In an effort to identify the influence of light and temperature on the physiology and leaf structural characteristics of three species of Quercus from Coahuila, Mexico, we measured a comprehensive suite of plant traits as functions of light and temperature intensity. We tested the hypotheses that 1) species' physiological responses to light and temperature were related to their distributions in their native habitats; and 2) that species' physiological responses corresponded to similar variation in leaf anatomical and morphological traits. Quercus sideroxyla was adapted to high elevation forest over stories as evidenced by its high photosynthetic rate, transpiration rate, relative water content (RWC), leaf density (LD), and thick palisade and spongy parenchyma. Quercus rugosa displayed typical characteristics of a forest understory species including a low photosynthetic rate and light saturation point, thick spongy parenchyma tissue and high RWC, leaf density, and leaf mass per unit area. Quercus laceyi was adapted to hot, dry sites based on its lower RWC and LD, intermediate photosynthetic rate, thick cuticle and upper epidermis, and low transpiration rates at high temperatures. Our results suggest that the physiological and structural adaptations of Mexican oaks to changing environmental conditions across resource gradients are key regulators of plant community structure.
    • Piman Indian Historic Agave Cultivation

      Dobyns, Henry F.; Newberry Library (University of Arizona (Tucson, AZ), 1988)
      The lands occupied by northern Piman Indians yet display remains of old ways of life, the hallmark being ruins of massive "casa grande" style architectural complexes within puddled adobe walled compounds. Vestiges of "rockpile" fields occur on desert bajadas that seem to have little potential for traditional hispanic or anglo agriculture. Evidence has accumulated that critical population pressures once exerted heavy demands on the food supply in this region, with resultant internecine strife and competition, the massive walled architectural complexes functioning as defensible storehouses for food that was harvested from the resource area controlled or exploitable by the inhabitants. The rockpile fields were used for agricultural production of the sweet foodplant Agave, using an innovative technology that made use of agriculturally marginal land (see Desert Plants Volume 7, pp. 107 -112, 100). The European encounter of Pimans occurred to the south long before it occurred to the north, at a time when ways of life were rapidly changing. A rare glimpse of southern Piman life about 1613 by Rev. Andrés Pérez de Ribas presents an historic picture of Agave cultivation by people living in houses with massive puddled adobe walls. This Piman way of life at that time in the southern region is altogether consistent with the vestiges of what seems to have been the same lifestyle in the north. Old World diseases brought a general collapse of Native American populations; the pressures that generated casa grande style architecture, earth defensive walls, and Agave cultivation in Piman territory diminished, a terminal date for the complex more likely to have been after A.D. 1613 than the traditional date of "Classic Hohokam" demise about A.D. 1450. Introduction of Old World cultivars high in sugar (melons, peaches, apricots, quinces, pears, apples, sugar cane) also reduced Piman demand for sweet pulp of Agave. Watermelons were already substituting as a functional equivalent of Agave by 1698 among northern Pimans. Both the casa grande style ruins and the rockpile fields were abandoned by the time European civilization reached the northern Pimans. Both have been classified as "Hohokam" by archaeologists, using the plural of the Piman language word meaning "all used up" or "defunct."
    • Plains and Great Basin Grasslands

      Brown, David E.; Arizona Game and Fish Department (University of Arizona (Tucson, AZ), 1982)
    • Plains and Great Basin Riparian Wetlands

      Minckley, W. L.; Brown, David E.; Department of Zoology, Arizona State University; Arizona Game and Fish Department (University of Arizona (Tucson, AZ), 1982)
    • The Plant Collecting Brandegees, with Emphasis on Katharine Brandegee as a Liberated Woman Scientist of Early California

      Crosswhite, Frank S.; Crosswhite, Carol D.; Boyce Thompson Southwestern Arboretum (University of Arizona (Tucson, AZ), 1985)
    • Plant Geography of Southwestern Sand Dunes

      Bowers, Janice E. (University of Arizona (Tucson, AZ), 1984)
      Patterns of plant distribution among eight dune fields in the southwestern USA and northwestern Mexico are analyzed and discussed. Each dune flora is characterized by three to five geographic components; the regional flora in which each dune field occurs is the dominant component. Endemic species, that is, species restricted to sand dunes, comprise ten percent or more of five of the eight floras. All possible combinations of the eight dune floras taken two at a time (28 pairs) were analyzed using Sorensen's similarity index. Only seven have a similarity value of 0.200 or greater. The lack of similarity among dune floras is due in part to their distribution among four floristically distinct biogeographic provinces and in part to localized recruitment of species from adjacent, non -dune plant communities. Geographic, edaphic and temporal barriers to dispersal and establishment also promote high dissimilarity among the eight floras. Eighty -three of the 533 species composing the eight dune floras are either endemic to sand dunes or occur at three or more of the dune fields studied. These 83 species fall into two subgroups: a group of 36 species characteristic of southwestern sand dunes east of 113° Longitude, and a group of 57 species characteristic of sand dunes west of 113° Longitude. Ten species are common to both groups. In the Southwest, dune fields are habitat islands, but dune floras do not behave in all respects as predicted by the MacArthur and Wilson theory of island biogeography. Southwestern sand dunes are not now floristic islands, but additional insular characteristics may develop over time.