Desert Flora Research Articles

Hacia una fitogeografía histórica del Desierto de Atacama

The concept of floristic element is fundamental in historical biogeography. In this work the floristic boundaries of the Atacama Desert as well as the biogeographical relationships that have been proposed for the area are reviewed. In an attempt to identify floristic elements of the Atacama Desert, the phyIogenetic literature is reviewed and integrated with the knowledge about the geographical distribution of lineages present in the Atacama Desert. Four floristic elements were identified: (i) neotropical, (ii) Central Chilean, (iii) transandean and (iv) antitropical. These elements are discussed in the context of the possible geographical origins of the Atacama Desert flora.

Introducing short roots in a desert perennial: anatomy and spatiotemporal foraging responses to increased precipitation

• The desert flora possesses diverse root architectures that result in fast growth in response to precipitation. We introduce the short root, a previously undescribed second-order root in the aridland chamaephyte Cryptantha flava, and explore fine root production. • We describe the short root anatomy and associated fine roots, correlate standing fine root crop with soil moisture, and explore the architectural level - the short root, third-order lateral roots, or the whole root system - at which fine roots are induced by watering and the amount of water required. • We show that short roots are borne at intervals on lateral roots and produce fine roots at their tips; new fine roots are white and have root hairs, while brown and black fine roots are apparently dead; and fine root production is triggered at the level of lateral roots and with relatively low precipitation (≤ 2 cm). • Short roots are suberized and thus are probably not capable of water uptake themselves, but serve as initiation sites for fine roots that grow rapidly in response to rainfall. Thus, C. flava should be a beneficiary of projected precipitation increases in habitats where rainfall is pulsed.

Eastern and Central Arrernte picture dictionary (review)

Reviewed by: Eastern and Central Arrernte picture dictionary Nick Thieberger Neil Broad, with Eastern and Central Arrernte speakers (compilers). 2008. Eastern and Central Arrernte picture dictionary. Alice Springs: IAD Press. x + 179 pp. ISBN 978-186465-0709. $Aust. 24.95. This latest in a long list of picture dictionaries from the Institute for Aboriginal Development (IAD) Press presents words arranged under fifty topics in Eastern and Central Arrernte (which is the name for a single variety of this Central Australian Pama-Nyungan language), with pictures representing those words, often together with an example sentence. The first 93 pages of the A4 format book display pictures and words with an example sentence (that attempts to "bring into focus some aspect of Arrernte cultural knowledge") entirely in the language, with the next 40 or so pages providing translations of the same terms into English. There are two short texts (60, 68), a kinship diagram (12), and a map of local placenames (20–21). This is all followed by an Eastern and Central Arrernte-to-English wordlist, and then an English finderlist. The final seven pages provide a pronunciation guide. The book is wrapped with an attractive dot painting cover by Amunda Gorey. While the language is identified with a geographic designation ("Eastern and Central"), it is a variety of Arrernte that has its own internal variation, indicated by cardinal directions—(E), (N), (W), (S)—appended to relevant words in the wordlist and finderlist. The idea for a picture dictionary appears to have come out of a meeting of speakers of Anmatyerr (another Arandic Central Australian language) in 2001, which identified the need to create language materials that would be useful for school children. The IAD picture [End Page 316] dictionary (as template) aims to present a set of some 800 words that can be adapted for use with any Australian language (although the focus is on desert flora and fauna), with more than 400 beautiful line drawings depicting local life, both natural (e.g., twelve images of reptiles, fifty of birds, lots of plants, bush foods, medicines, and grubs) and cultural (e.g., cooking and food preparation, what's happening, weapons, and tools). As these headings indicate, the words are from a range of classes, not just nouns, and illustrations depict both objects and actions. The definitions and examples are not intended to be as detailed as in a full dictionary; for example, awelye is a 'healing song', with the rather opaque example sentence Awelye antere alyeke-arle 'The traditional healer sings the fat with a healing song'. The dictionary of Eastern and Central Arrernte (Henderson and Dobson 1994) is one of the most detailed dictionaries of an Australian language, and readers interested in more information can refer to the larger work. In addition to the many language terms provided, there is also a section on "today's things" that includes terms adapted for introduced items, e.g., apwerte 'money' (from 'hill'), pute 'shoe, boot', rapite 'rabbit, nanikute 'goat', and peke-peke 'pig' (but marnte 'bus' is in the "what's happening" section, as are the more transparent loans pathekale 'bicycle' and mwetekaye 'car '). Since about half of the entries in the wordlist begin with a, this section is further divided to include subsections beginning with ah, ak, al, am, an, and so on. This makes sense, in that it breaks up what would otherwise be eight pages of wordlists. Typos are not that easy to spot for a nonspeaker of Arrernte, but the word tyerrtye appears after an example sentence (98) when it does not seem to belong there. IAD Press has established a well-deserved reputation for producing language materials, from introductory story books and learner's guides, through to detailed dictionaries. To date, Australian languages represented using the picture dictionary template include Alyawarr, Central Anmatyerr, Gamilaraay/Yuwaalaraay, Kaytetye, Ngaanyatjarra, Pitjantjatjara/Yankunytjatjara, Warumungu, and Western Arrarnta. Nick Thieberger University of Melbourne and University of Hawai'i at Mānoa Reference Henderson, John, and Veronica Dobson. 1994. Eastern and Central Arrernte to English dictionary. Alice Springs: IAD Press. [End Page 317] Google Scholar Copyright © 2010 University of Hawai'i Press

Phytogenic resources of halophytes of Central Asia and their role for rehabilitation of sandy desert degraded rangelands

AbstractBased on soil characteristics, watertable level, mineral composition of plant biomass, morphological/reproductive traits and carbon discrimination values, a new concept for the classification of halophytes was developed. Six main groups of halophytes have been described within the desert flora of Central Asia. Significant changes on chemical contents of ions: Cl−, SO, HCO, Na+, K+, Ca2+ and Mg2+among 23 studied halophytic forage species were revealed. Alhagi pseudoalhagi, Poaceae spp., Artemisia diffusa containing minimum concentration of mineral ions were categorised as relatively more palatable and valuable feed for livestock on open grazing and as hay. Fresh biomass of forage species growing under highly saline soils sharply decreased with increasing of salinity gradient. Potassium concentration was found highest in Kochia scoparia, Agropyron desertorum, closely followed by Atriplex nitens, Suaeda salsa, while annuals Salsola spp., Bromus tectorum, Aeluropus littoralis, Tamarix hispida, Eremopyrum orientale, Agropyron desertorum contain low amount of mineral ions because excess of salts are exuded through salt glands present abundantly on the surface of the epidermis. Native and exotic, both C3 and C4, halophytes are suitable for reclamation of degraded lands have been proven very useful in demonstration trials. The fresh biomass of investigated C3 plants sharply decreased with the increasing of soil salinity gradient. An integrated Biosaline Agriculture model for sustainable and integrated use of marginal mineralised water resources and salt‐affected soils through involvement of food–feed salt/drought tolerant crops and forage legumes to improve food security, alleviate poverty and enhance ecosystem health in smallholder crop–livestock systems has been demonstrated. Copyright © 2009 John Wiley & Sons, Ltd.

Evolving restoration principles in a changing world

Evolving restoration principles in a changing world

Responses of Caragana korshinskii Kom. to shoot removal: mechanisms underlying regrowth

AbstractCaragana korshinskii Kom. a dominant member of desert flora in north‐western China, is often subjected to aboveground shoot destruction but is very successful in its rapid recovery. We investigated the physiological basis for resprouting by comparing shoot elongation, leaf‐nutrient content, pre‐dawn leaf‐water potential (LWP), root non‐structural carbohydrate (TNC), and photosynthetic rate of first‐year resprouts with those of adjacent undamaged individuals. C. korshinskii resprouts had a significantly higher rate of shoot elongation. Plant responses associated with enhanced shoot elongation included (1) improved water status, (2) drawing upon more TNC from roots to support aboveground shoot regrowth, (3) enhanced photosynthetic rate owing to improved water status and increased nutrient content in leaves, and (4) allocating more photosynthate to vegetative production without reproduction costs. Maintaining an active root system after shoot removal may be the foundation which engenders these mechanisms underlying rapid regrowth of C. korshinskii in the disturbed environment.

Molecular evidence for the age, origin, and evolutionary history of the American desert plant genus Tiquilia (Boraginaceae)

Although the deserts of North America are of very recent origin, their characteristic arid-adapted endemic plant lineages have been suggested to be much older. Earlier researchers have hypothesized that the ancestors of many of these modern desert lineages first adapted to aridity in highly localized arid or semi-arid sites as early as the late Cretaceous or early Tertiary, and that these lineages subsequently spread and diversified as global climate became increasingly arid during the Cenozoic. No study has explicitly examined these hypotheses for any North American arid-adapted plant group. The current paper tests these hypotheses using the genus Tiquilia (Boraginaceae), a diverse North American desert plant group. A strongly supported phylogeny of the genus is estimated using combined sequence data from three chloroplast markers ( matK, ndhF, and rps16) and two nuclear markers (ITS and waxy). Ages of divergence events within the genus are estimated using penalized likelihood and a molecular clock approach on the ndhF tree for Tiquilia and representative outgroups, including most of the major lineages of Boraginales. The dating analysis suggests that the stem lineage of Tiquilia split from its nearest extant relative in the Paleocene or Eocene (∼59–48 Ma). This was followed by a relatively long period before the first divergence in the crown group near the Eocene/Oligocene boundary (∼33–29 Ma), shortly after the greatest Cenozoic episode of rapid aridification. Divergence of seven major lineages of Tiquilia is dated to the early-to-mid Miocene (∼23–13 Ma). Several major lineages show a marked increase in diversification concomitant with the onset of more widespread semi-arid and then arid conditions beginning in the late Miocene (∼7 Ma). This sequence of divergence events in Tiquilia agrees well with earlier researchers’ ideas concerning North American desert flora assembly.

My Contributions to Science and Society

My Contributions to Science and Society

Master Gardener-led Projects in Southern Nevada

Southern Nevada Master Gardeners (MGs) donate 50 hours annually to educational and service projects. These volunteers respond to community needs by developing and staffing horticultural projects under UNCE supervision. In Las Vegas, 20 such projects exist. Some are more energy and information intensive than others. Mojave Guides are docents at the Desert Demonstration Garden, a part of the Las Vegas Springs Preserve, not Extension. They commit to a shift at the garden, providing information to visitors. While they are directly supervised by garden staff, the hours they contribute are Master Gardener hours. These volunteers receive training in desert flora from gardens staff and participate in seminars on selected topics. The MG Orchard Team operates a teaching orchard at the Center for Urban Water Conservation in North Las Vegas. These volunteers maintain hundreds of fruit trees and grape vines. They receive training on topics related to fruit trees and orchard management. This project began in 1996. Since 2002, they have been formalizing their organization using the logic model and SWOT analysis. Many members work weekly at the orchard and take the produce to a local farmers market. This raises funds for the orchard and is an opportunity to teach the community about desert horticulture. Project PLANT volunteers work at the Red Rock National Recreation Area visitor center and grounds. They are docents who also learn about and maintain the native plants there, and prevent infestations of invasive weeds which threaten the area. Their monthly meetings include training on topics related to the project. These projects are successful because of the MGs themselves. They grew out of interest and continue because the volunteers have drawn commitment from others.

Recent environmental change and prehistoric human activity in Egypt and Northern Sudan

This paper reviews the various Late Quaternary records that are available from western Egypt and northern Sudan, which includes more than 500 published radiocarbon dates and various sedimentary archives from local landscape components, including palaeolakes, soils, drainages (wadis), and archaeological sites. This palaeoenvironmental compilation frames the spatial and temporal context of local cultural activities when the region was most hospitable ∼9000–6000 BP; at this time, monsoonal weather influenced the portion of the African continental interior, creating enough convective rainfall for occasional surface water storage. In this part of the modern Sahara, rapid hydroclimatic changes play a key role in geomorphic evolution and resource availability. As ‘watering holes’ formed and dried up in the Early to Middle Holocene, Neolithic people developed various subsistence strategies, including opportunistic hunting of small animals (e.g. gazelle and hare), and food-related (e.g. wild sorghum, millet, and legumes) activities: gathering, plant cultivation and livestock-rearing. During its wettest phases during the ‘monsoonal maximum,’ the area was drought-prone, sustaining a meager steppe–shrub desert flora. Further desertification and aeolian deflation during the Middle and Late Holocene fostered technological innovation, migration and settlement, as well as the further development of agrarian communities and complex culture.

Fear Falls Away and Other Essays from Hard and Rocky Places by Janice Emily Bowers

b o o k Re v ie w s 2 1 3 layered over a difficult relationship with her father that Legler tries to sal­ vage or at least explain. The central argument for the collection comes almost in the middle, with Lorde’s “erotic charge” extended to Legler’s connections with hunting, preparing, sharing, and eating the things that she has killed; her charge as a sexual being; her charge as a member of a community (of writers, teachers, lesbians, friends, family). The beauty and texture of the collection is seen best in the open-ended pondering in the final chapter. Legler is camping with a group of women in the northern Minnesota boundary waters, and a friend is recounting an experience viewing the northern lights. Legler represents the tone of the entire collection and its pull between the natural world, self, and awareness when she says, “You always must go back to your own particular life with a vague ache in your heart; an ache that suggests to you there is another place you should be, although you don’t know where it is” (182). The collection does not conclude so much as end with reiterated connections to the intan­ gible world, but the honesty of the quest is compelling. F ear Falls Away and Other Essays from Hard and Rocky Places. By Janice Emily Bowers. Tucson: University of Arizona Press, 1997. 175 pages, $35.00/$ 16.95. Reviewed by Sarah L. Bennett U tah State University Following Janice Emily Bowers through the pages of Fear Falls Away is like spending the day with a favorite hiking partner whose lively step, keen observations, and graceful insight can reveal the life and beauty of a land­ scape and nurture the soul. With the heart and earnestness of a poet and the eye of a painter, Bowers considers the mountainscapes around her home in Tucson from a perspective that is at once intimate and vast, but always human. Faced with the possibility of having to leave her beloved desert home after more than twenty years, Bowers revisits her favorite canyons and ridgelines as scientist, artist, and pilgrim, seeking an understanding of the many threads that tie her to those sacred places. Formally trained and employed as a botanist, and regionally recognized as a writer and naturalist (A Full Life in a Small Place and Other Essays from a Desert Garden, 1995), Bowers has an enormous wealth of information to share on the life processes of that region’s desert flora and fauna. Bowers offers treasures in gratitude and celebration of place: the precise conditions in which brittlebrush seeds can germinate; a woodpecker gathering and storing acorns in a snag used by generations of his kind where “[t]he tree seems to have a hundred brown eyeballs” (28); light playing in the irides­ cent feathers of a hummingbird’s chin; butterflies “mudding” on wet sand near a seep. These details are gifts, not rulers with which Bowers measures her intellect or raps our knuckles in order to gain our attention. And while 2 1 4 WAL 3 3 ( 2 ) S u m m e r 1 9 9 8 she often requires we stoop to put eye to flower or darting bird, or pause to glance upward toward a ridge or a wheeling raptor, the effortless stride of her prose and her story are not broken but continue upward toward high places. Bowers takes special care not to leave us off the trail somewhere overcome with awe in a mystical daze but instead grounds us in the profound attachments we make to the wild places we love in the context of everyday human realities. Perhaps this is what is most successful and most important about Fear Falls A way. Forced to consider leaving southern Arizona initiates a thoughtful exploration of Bowers’ own internal, as well as surrounding external, landscapes where she considers the behavioral, emotional, and psychological adaptations we, as a species, make to place. Recognition of the ongoing evolutionary symbiosis humans share with their natural surroundings is a constant theme throughout these essays and a noteworthy undertaking for a nature writer. The rock art of the Hohokam who once lived...

Preliminary assessment of the gulf war on Kuwaiti desert ecosystem

Abstract Various important resources of the desert environment were devastated during the Iraqi occupation of Kuwait and the Gulf War. These resources include; soil, plants and animals. In addition, to the man‐made soil disturbance problems which already existed prior to the Gulf turmoil, new factors were introduced such as; oil pollution, mines placement and tank movement within the fragile desert soil. Polluted soils were characterized by three kinds; oil logged soil close to the burnt oil wells, soil covered with oil mist and lightly affected soil by the soot fallout. The purpose of this paper is to highlight the impact of the Gulf crisis and mainly the burning of oil wells on Kuwait's desert flora, fauna and soil. Plant and soil samples were analysed for total hydrocarbons and heavy metals. The wild life of Kuwaiti deserts were also evaluated.

Plant Life-Forms and Biogeographic Relations of the Flora of Lagunillas (30 | circS) in the Fog-Free Pacific Coastal Desert

The coastal desert of north-central Chile supports a rich but poorly known flora. Here, we document the importance of the annual and perennial habits in the flora of Lagunillas (30°S), at the southern transition from the desert to the mediterranean climate region, and discuss the origin of the desert flora by examining the geographic distribution of the taxa at the level of genus. The distribution was used to assign the species to six biogeographic elements. Annual plants represent 41% of the total flora (191 species) and are the most important life form. Excluding non-native weeds, however, decreases the importance of annuals to 33%. This value is higher than that for high-altitude deserts, but lower than for most other, less-equitable, lowland deserts both in North America and eastern Asia (...)

Speciation and Persistence of a Contact Zone in Mojave Desert Ground Squirrels, Subgenus Xerospermophilus

Genetic intergradation between Spermophilus mohavensis and S. tereticaudus , estimated from cranial morphometrics, is restricted to known and purported sites of hybridization. The boundary between the two species coincides with the Wisconsinan distribution of pluvial lakes and river systems, which isolated a cooler, more mesic refugium of Mojave Desert flora and fauna during pluvial maxima. A continuous barrier was last present 10,000 years ago, but disappeared at least 6,000 years ago. Subsequent range expansion of either species across this previous barrier has been limited to 30 km, or an average of ≤5 m/year. Persistence of the initial contact zone may result from low vagility of both species, incorporation of rare immigrants through introgressive hybridization, competition, or a combination of these factors.

Plant Ecology of the Namib Desert

The Namib desert is reportedly the oldest desert in the world. It consists of a number of very distinct ecosystems, six of which are dealt with in this text. Among them are the sand dune, the dry river bed and the domed inselbergs vegetation. The importance of fog water absorption for the Namib flora is discussed. Two important and noteworthy endemic plant species, i.e. Welwitschia mirabilis and Acanthosicyos horrida are treated extensively, because of their great interest for plant physiology and ethnobotany, resp. Special attention is given to the importance of the CAM photosynthetic system for Namib desert plant survival. Where possible the ethnobotanic importance of the species is discussed. KEY WORDS: Acanthosicyos horrida. desert flora, drought stress, ethnobotany, succulents, Welwitschia mirabilis

A Historical Sketch of the Vegetation of the Mojave and Colorado Deserts of the American Southwest

The Mojave and Colorado Deserts of the American Southwest are geologically recent in origin, resulting primarily from the rain-shadow caused by the Late Pliocene-Pleistocene elevation of the Sierra Nevada, Transverse, and Peninsular ranges. Their age thus is perhaps two to three million years. The present vegetation is even more recent, largely Holocene in origin, and still evolving. During the last, Wisconsin, glacial episode the California deserts were well supplied with huge, deep lakes and large streams and an open woodland, possibly grassy, supporting numerous large mammals, now mostly extinct. The desert flora, however, is in large part more ancient, having been assembled since early Paleogene time from many sources. Most of the perennials are probably former members of the Madro-Tertiary Geoflora that dominated southern California and adjacent areas during the Tertiary. They are species of dry habitats preadapted to long periods of drought, hot, dry summers, and cool, wet winters and thus able to populate and adapt to the varied desert habitats when they became available. They survived cool, pluvial, glacial periods by migration southward or to lower elevations. Some elements of the American southwestern desert flora are derived from Mexico, South America, central Asia, and a few possibly from North Africa and the Mediterranean region by overland immigration or long distance dispersal. In some instances this was aided by changing ocean size due to continental movement, glacial sea-level lowering, and to changes in oceanic-current patterns. Some desert plants, at least some of the ephemerals, may well be of very recent, even Holocene, origin in our arid Southwest. Those of us without much geological training, in view of our own brief life span, tend to think of large-scale features of the landscape as rather permanent, thus very ancient. Yet geologists assure us that large lakes, islands, mountains, and the deserts behind them are relatively ephemeral in the geological time scale. Our southwestern deserts are no exception. The existing regional deserts or semi-deserts are geologically recent, possibly only a couple of million years old, at least as we know them today. They are essentially products of the late Pliocene-Pleistocene elevation of the Sierra Nevada, Transverse, and Peninsular ranges in southern California, which created a huge rain-shadow to the east. Thus, most of the moisture gleaned from the Pacific Ocean by the prevailing westerly winds precipitated on the western slopes of the ranges. As the air masses descended the transmontane slopes, they heated up adiabatically and became a drying force.

A Revision of Samolus ebracteatus (sensu lato) (Primulaceae)

A revision of the Samolus ebracteatus-cuneatus complex is presented recognizing five varieties of S. ebracteatus: S.e. var. ebracteatus from the Caribbean and Florida; var. alyssoides from coastal Texas to Mexico; var. cuneatus from inland Texas to Nevada and central Mexico; var. coahui- lensis (var. nov.) from central Coahuila; and var. breviflorus (var. nov.) from southern Mexico. Preparation of a treatment of Samolus L. for M. C. Johnston's Chihuahuan Desert Flora has lead to this revision of the entire Samolus ebracteatus-cuneatus complex. This was necessary to properly accommodate a new taxon from central Coahuila. Three taxa have been described within this complex. All are relatively similar in vegetative and floral characteristics (Fig. 1) and distinguished from other species in the genus by the absence of bracts on pedicels and absence of distinct epipetalous staminodia attached to the corolla tube and alternate to its lobes (Pax and Knuth, 1905). Samolus ebracteatus was described by Kunth (1815) from a collection by Humboldt and Bonpland from southern Cuba near Batabano, south of Havana. While the original description and illustration make no note of stipitate glands, study of other specimens from the type locality indicate that material from Cuba, Florida, and the West Indies are all similar and characterized by stipitate glands on pedicels, inflorescence axes, and moderately large, mostly pinkish-white corollas. A second taxon, S. alyssoides was described by Heller (1895) from a sandy habitat along the east coast of Texas. He distinguished the new species from S. ebracteatus on the basis of growth habit, emphasing its erect, more compact nature in contrast to a more leafy, spreading habit of S. ebracteatus. He also noted the new taxon had glaucous leaves and larger flowers than S. ebracteatus. Though not noted by Heller, S. alyssoides differs from Floridian-West Indian populations of S. ebracteatus by the lack of stipitate glands on pedicels and inflorescence axes. In that paper, Heller (1895) also cites a collection of S. ebracteatus from near Kerrville, Texas which he apparently had used to contrast his S. alyssoides. He distributed the specimens of that collection identified as a new species, but never published the new name. In 1897 Small cited Heller's Kerrville specimen as the type of a new species S. cuneatus noting it could be distinguished from S. ebracteatus and S. alyssoides by its smaller flowers measuring only 4-5 mm (not 6-9 mm) in breadth and by its more cuneate (not suborbicular) petal lobes. Like the Floridian-West Indian specimens of S. ebracteatus it also has stipitate glands on the pedicels and inflorescence axes.

Why are adaptations for long-range seed dispersal rare in desert plants?

The rarity of long-range seed dispersal (telechory) and commonness of antitelechory in desert plants are examined in light of contemporary mathematical theories of the evolution of dispersal and germination behaviors. Analysis of dispersal 3-habitat relationships in the flora of Israel supports the general trend towards atelechory in deserts; in particular epizoochory and tumbleweeds are practically absent from the desert and heterocarpy is centered in the Mediterranean region. In contradiction to the accepted "mother-site" theory, we find that (a) there is a high turnover in microscale spatial pattern among antitelechoric species; (b) antitelechoric (especially basicarpic) species are widespread and dominant in the desert vegetation of Israel; (c) amphicary and geocary are rare in the desert flora of Israel.We argue that the openness of desert vegetation and the patterns of climatic variation favor atelechory while antitelechory is generally a side-effect of mechanisms whose adaptive value is not directly related to dispersal. Thus for example the desert plants of Israel have evolved a variety of dispersal-restricting seed-containers that protect the seed from predation and flooding, regulate the within-season timing of germination, and spread dispersal and germination over several years.

Full-Glacial and Recent Vegetation of Livingston Hills, Presidio County, Texas

A fossil packrat midden from 1280 m elevation in the limestone Livingston Hills south of Shafter, Presidio County, Texas, was radiocarbon dated at 15,695 ? 230 B. P. (A-1581 on Juniperus). The paleocommunity was a pinyonjuniper woodland with Pinus edulis and 26 associated species. Holacantha stewarti was an important desert species in the paleocommunity. A total of 139 species was recorded in the present xeric Chihuahuan Desert flora near the midden site. Late Pleistocene paleocommunities and the timing of biotic changes in the northern Chihuahuan Desert are discussed. The Chihuahuan Desert reaches its lowest elevations along the United States-Mexico International Boundary along the Rio Grande in the Big Bend of Texas. The varied geology and vegetation of the region produce as scenic a painted desert landscape as any in the southwestern deserts. However, the desert has not been in the Big Bend for long. Wells' (1966) analysis of fossil packrat (genus Neotoma) middens from the Big Bend found a xeric woodland with pinyon (Pinus cembroides var. remota) as low as 600 m elevation in Maravillas Canyon during the last glaciopluvial period. His sites were from 600 to 1200 m elevations in three areas peripheral to the Chisos Mountains. Wells (1977) suggested that the present Chihuahuan Desert vegetation entered the Big Bend less than 11,500 years ago. Here we report a late Pleistocene plant macrofossil assemblage from an ancient packrat midden from the west side of the Big Bend in the Livingston Hills (Fig. 1).

Potentialities of plants with underground storage organs in the Egyptian desert flora

Plants with underground storage organs in the natural flora of Egypt appeared promising as raw materials for various economic uses. As basic information for any future industrial, pharmaceutical, or agricultural uses, we must understand their inorganic constituents in relation to variations of habitats and life cycle events. Fourteen species have been collected from different habitats along the Mediterranean coast and examined for their chemical element composition and correlated with the environmental conditions. One of these species,Asphodelus microcarpus Salzm. and Viv., has been critically studied to determine the uptake and distribution of the different mineral elements during its different phenophases. The importance of this study on the rational uses of the different parts of this plant is discussed.