Bursera microphylla is a North American species of tree in the frankincense family in the soapwood order. Bursera microphylla, known by the common name elephant tree in English or'torote' in Spanish, is a tree in genus Bursera, it grows with a thickened, water-storing or caudiciform trunk. It is found in the southwestern United States and northwestern Mexico. Bursera microphylla is the most northerly member of the Burseraceae in North America and perhaps the most xeromorphic species within the genus as it thrives in the arid desert hills and mountains in northwest Sonora; this tree is native to northwestern Mexico and the southwestern United States (southern California and Arizona. Some of the populations lie inside Anza-Borrego Desert State Park, Organ Pipe Cactus National Monument, Cabeza Prieta National Wildlife Refuge, Ironwood Forest National Monument, Sonoran Desert National Monument and Gran Desierto Biosphere Reserve, Islas del Golfo de California Biosphere Reserve, Cabo Pulmo National Park, El Vizcaíno Biosphere Reserve, Valle de los Cirios Natural Protected Area, Sierra de San Pedro Mártir National Park.
Bursera microphylla is a small tree with a thickened trunk and small branching structure in comparison to the trunk size. Shreve classified the plant as a sarcocaulescent tree; the sarcocaulescent habit acts as a buffer against variation in environmental water balance. The leaves are alternate, without stipules, are once-pinnate or twice-pinnate but can be unifoliate or trifoliate in some species. Bursera microphylla reaches up to 10 m in height and its bark is light gray to white, with younger branches having a reddish color; the light foliage is made up of long, flat, legume-like leaves which are composed of paired leaflets. It flowers in rounded yellow buds which open into star-shaped, white or cream flowers; the fruit is a drupe containing a yellow stone. The leaves are characterized as deciduous, including those on species that occur in tropical subhumid and humid forests; as a response to rain and warmer temperatures, B. hindsiana, B. laxiflora, other more tropical species in Sonora begin to leaf out at any time of the year.
Most species are drought deciduous, but B. microphylla keeps its leaves year-round, except under conditions of drought and cold weather. Most of the Sonoran Burseras flower in June and July, just before or just as the leaves are produced; this is in response to a lack of rainfall earlier in the summer before the monsoon season as this species is found in the region of Sonora lies at the western edge of an area, which experiences summer monsoon storms. The fruits of species in the genus Bursera are each with a single-seed. In B. microphylla, the fruits develop and ripen a few at a time, in some species many fruits remain on the trees as they begin to flower the following summer. Birds appear to be responsible for seed dispersal in Bursera. Gray Vireos and Ash- throated Flycatchers feed on the ripe fruits of B. microphylla in the Puerto Lobos region of Sonora, Mexico during the winter months. The winter range of the Gray Vireo in Sonora matches the distribution of Bursera microphylla. Birds do not appear to eat the unripe fruit.
Rodents sometimes gather seeds of Bursera. Ants have been observed carrying away seeds of B. microphylla<. The exfoliating papery bark of many of the trivalvate species may serve to attract the attention of birds and other animals from a distance as it rustles in the breeze; the Cahuilla Indian people of the Colorado Desert region of California used the red sap of the elephant tree for treating skin disorders and other diseases. Seri use the plant in many ways, including the wood for boxes, it is popular as a landscape plant in southwestern US in low warm desert. Bursera fagaroides Jepson Manual Treatment — Bursera microphylla Bursera microphylla — Calphotos Photo gallery, University of California
Baja California Peninsula
The Baja California Peninsula is a peninsula in Northwestern Mexico. It separates the Pacific Ocean from the Gulf of California; the peninsula extends 1,247 km from Mexicali, Baja California in the north to Cabo San Lucas, Baja California Sur in the south. It ranges from 40 km at its narrowest to 320 km at its widest point and has 3,000 km of coastline and 65 islands; the total area of the Baja California Peninsula is 143,390 km2. The peninsula is separated from mainland Mexico by the Gulf of the Colorado River. There are four main desert areas on the peninsula: the San Felipe Desert, the Central Coast Desert, the Vizcaíno Desert and the Magdalena Plain Desert; the land of California existed as a myth among European explorers. The earliest known mention of the idea of California was in the 1510 romance novel Las Sergas de Esplandián by Spanish author Garci Rodríguez de Montalvo; the book described the Island of California as being west of the Indies, "very close to the side of the Terrestrial Paradise.
Following Hernán Cortés' conquest of Mexico, the lure of an earthly paradise as well as the search for the fabled Strait of Anián, helped motivate him to send several expeditions to the west coast of New Spain in the 1530s and early 1540s. Its first expedition reached the Gulf of California and California, proved the Island of California was in fact a peninsula; the idea of the island persisted for well over a century and was included in many maps. The Spaniards gave the name Las Californias to the peninsula and lands to the north, including both Baja California and Alta California, the region that became parts of the present-day U. S. states of California, Utah and parts of Colorado and Wyoming. 1532: Hernán Cortés sends three ships north along the coast of Mexico in search of the Island of California. The three ships disappear without a trace. 1533: Cortés sends a follow-up mission to search for the lost ships. Pilot Fortún Ximénez leads a mutiny and founds a settlement in the Bay of La Paz before being killed.
1539: Francisco de Ulloa explores both coasts. 1622: A map by Michiel Colijn of Amsterdam showed California as a peninsula rather than an island. Previous maps show the Gulf terminating in its correct location. 1690s–1800s: Spanish settlement and colonization in lower Las Californias, the first Spanish missions in Baja California are established by Jesuit missionaries. 1701: Explorations by Eusebio Kino expanded knowledge of the Gulf of California coast. Kino did not believe. 1767: Jesuits expelled. 1769: Franciscans go with the Portola expedition to establish new missions in Alta California. Control of the existing Baja missions passes to the Dominican Order. 1773: Francisco Palóu's line demarcates Franciscan and Dominican areas of mission control. 1804: Las Californias divided into Alta and Baja California, using Palóu's line. 1810–1821: Mexican War of Independence 1821: First Mexican Empire, Baja California Territory established, covering Baja California Peninsula. 1847: The Battle of La Paz and the Siege of La Paz occurs, as well as several other engagements.
1848: Treaty of Guadalupe Hidalgo cedes Alta California to the United States. As a U. S. territory it receives the California Gold Rush, causing increased maritime traffic along the peninsula. 1850: California admitted to U. S. statehood. 1853: William Walker, with 45 men, captures the capital city of La Paz and declares himself President of the Republic of Lower California. Mexico forces him to retreat a few months later. 1930–31: The Territory of Baja California is further divided into Northern and Southern territories. 1952: The North Territory of Baja California becomes the 29th State of Mexico, Baja California. The southern portion, below 28°N, remains a federally administered territory. 1973: The 1,700 km long Trans-Peninsular Highway, is finished. It is the first paved road; the highway was built by the Mexican government to improve Baja California's economy and increase tourism. 1974: The South Territory of Baja California becomes the 31st state, Baja California Sur. The province of the Californias was united until 1804, in the Spanish colonial Viceroyalty of New Spain, when it was divided into Alta and Baja California.
The two Californias division was kept after Mexican independence in 1821. The Spanish Baja California Province became Mexican Baja California Territory, remained a separate territory until 1836. In 1836, the Siete Leyes constitutional reforms reunited both Californias in the Departamento de las Californias. After 1848, the Baja California Peninsula again became a Mexican territory when Alta California was ceded to the United States. In 1931 Baja California Territory was divided into southern territories. In 1952, the "North Territory of Baja California" became the 29th State of Mexico as Baja California. In 1974, the "South Territory of Baja California" became the 31st state as Baja California Sur; the northern part is the state of Baja California. The citizens of Baja California are named bajacalifornianos. Mexicali is the capital; the southern part, below 28° north, is the state of Baja California Sur. The citizens of Baja California Sur are named sudcalifornianos. La Paz is its capital
San Lucan xeric scrub
The San Lucan xeric scrub is a xeric shrubland ecoregion of the southernmost Baja California Peninsula, in Los Cabos Municipality and eastern La Paz Municipality of southern Baja California Sur state, Mexico. The San Lucan xeric scrub covers an area of 3,900 square kilometers, it extends from sea level at the coasts up to 250 metres elevation in the Sierra de la Laguna, where the Sierra de la Laguna dry forests ecoregion begins. Above that to the range's summits is the Sierra de la Laguna pine-oak forests ecoregion. Flora of Baja California Sur "San Lucan xeric scrub". Terrestrial Ecoregions. World Wildlife Fund. World Wildlife Fund, ed.. "San Lucan xeric scrub". WildWorld Ecoregion Profile. National Geographic Society. Archived from the original on 2010-03-08
Cnidoscolus is a plant genus of the family Euphorbiaceae first described as a genus in 1827. The group is widespread across much including the West Indies; the name is derived from the Greek words κνίδη, meaning "nettle," and σκολος, meaning "thorn" or "prickle." Species includedmoved to Astraea Jatropha C. obtusifolius - Jatropha mutabilis C. surinamensis - Astraea lobata Everitt, J. H.. L.. R.. Weeds in South Texas and Northern Mexico. Lubbock: Texas Tech University Press. ISBN 0-89672-614-2 Media related to Cnidoscolus at Wikimedia Commons Data related to Cnidoscolus at Wikispecies
In botany, a tree is a perennial plant with an elongated stem, or trunk, supporting branches and leaves in most species. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are usable as lumber or plants above a specified height. Trees are not a taxonomic group but include a variety of plant species that have independently evolved a woody trunk and branches as a way to tower above other plants to compete for sunlight. Trees tend to be long-lived, some reaching several thousand years old. In wider definitions, the taller palms, tree ferns and bamboos are trees. Trees have been in existence for 370 million years, it is estimated. A tree has many secondary branches supported clear of the ground by the trunk; this trunk contains woody tissue for strength, vascular tissue to carry materials from one part of the tree to another. For most trees it is surrounded by a layer of bark. Below the ground, the roots spread out widely. Above ground, the branches divide into smaller shoots.
The shoots bear leaves, which capture light energy and convert it into sugars by photosynthesis, providing the food for the tree's growth and development. Trees reproduce using seeds. Flowers and fruit may be present, but some trees, such as conifers, instead have pollen cones and seed cones. Palms and bamboos produce seeds, but tree ferns produce spores instead. Trees play a significant role in moderating the climate, they remove carbon dioxide from the atmosphere and store large quantities of carbon in their tissues. Trees and forests provide a habitat for many species of plants. Tropical rainforests are among the most biodiverse habitats in the world. Trees provide shade and shelter, timber for construction, fuel for cooking and heating, fruit for food as well as having many other uses. In parts of the world, forests are shrinking as trees are cleared to increase the amount of land available for agriculture; because of their longevity and usefulness, trees have always been revered, with sacred groves in various cultures, they play a role in many of the world's mythologies.
Although "tree" is a term of common parlance, there is no universally recognised precise definition of what a tree is, either botanically or in common language. In its broadest sense, a tree is any plant with the general form of an elongated stem, or trunk, which supports the photosynthetic leaves or branches at some distance above the ground. Trees are typically defined by height, with smaller plants from 0.5 to 10 m being called shrubs, so the minimum height of a tree is only loosely defined. Large herbaceous plants such as papaya and bananas are trees in this broad sense. A applied narrower definition is that a tree has a woody trunk formed by secondary growth, meaning that the trunk thickens each year by growing outwards, in addition to the primary upwards growth from the growing tip. Under such a definition, herbaceous plants such as palms and papayas are not considered trees regardless of their height, growth form or stem girth. Certain monocots may be considered trees under a looser definition.
Aside from structural definitions, trees are defined by use. The tree growth habit is an evolutionary adaptation found in different groups of plants: by growing taller, trees are able to compete better for sunlight. Trees tend some reaching several thousand years old. Several trees are among the oldest organisms now living. Trees have modified structures such as thicker stems composed of specialised cells that add structural strength and durability, allowing them to grow taller than many other plants and to spread out their foliage, they differ from shrubs, which have a similar growth form, by growing larger and having a single main stem. The tree form has evolved separately in unrelated classes of plants in response to similar environmental challenges, making it a classic example of parallel evolution. With an estimated 60,000-100,000 species, the number of trees worldwide might total twenty-five per cent of all living plant species; the greatest number of these grow in tropical regions and many of these areas have not yet been surveyed by botanists, making tree diversity and ranges poorly known.
The majority of tree species are angiosperms. There are about 1000 species of gymnosperm trees, including conifers, cycads and gnetales. Most angiosperm trees are eudicots, the "true dicotyledons", so named because the seeds contain two cotyledons or seed leaves. There are some trees among the old lineages of flowering plants called basal angiosperms or paleodicots. Wood gives structural strength to the trunk of most types of tree; the vascular system of trees allows water and other chemicals to be di
Cnidoscolus angustidens, with the common name mala mujer, is an herbaceous perennial plant in the spurge family. It is native to the Sonoran Desert mountains of southeastern Arizona and Northwestern Mexico, further south in Mexico."Mala mujer" is Spanish for "bad woman", referring to its stinging hairs which cause severe contact dermatitis. SubspeciesCnidoscolus angustidens subsp. Angustidens - Arizona, Mexico Cnidoscolus angustidens subsp. Calyculatus Breckon ex Fern. Casas - Michoacán Cnidoscolus angustidens subsp. Dentatus Breckon ex Fern. Casas - Jalisco, Puebla Cnidoscolus angustidens subsp. Orbiculatus Breckon ex Fern. Casas - C + S Mexico USDA Plants Profile for Cnidoscolus angustidens
An ecoregion is an ecologically and geographically defined area, smaller than a bioregion, which in turn is smaller than an ecozone. All three of these are either greater than an ecosystem. Ecoregions cover large areas of land or water, contain characteristic, geographically distinct assemblages of natural communities and species; the biodiversity of flora and ecosystems that characterise an ecoregion tends to be distinct from that of other ecoregions. In theory, biodiversity or conservation ecoregions are large areas of land or water where the probability of encountering different species and communities at any given point remains constant, within an acceptable range of variation. Three caveats are appropriate for all bio-geographic mapping approaches. Firstly, no single bio-geographic framework is optimal for all taxa. Ecoregions reflect the best compromise for as many taxa as possible. Secondly, ecoregion boundaries form abrupt edges. Thirdly, most ecoregions contain habitats. Biogeographic provinces may originate due to various barriers.
Some physical, some climatic and some ocean chemical related. The history of the term is somewhat vague, it had been used in many contexts: forest classifications, biome classifications, biogeographic classifications, etc; the concept of ecoregion of Bailey gives more importance to ecological criteria, while the WWF concept gives more importance to biogeography, that is, distribution of distinct biotas. An ecoregion is a "recurring pattern of ecosystems associated with characteristic combinations of soil and landform that characterise that region". Omernik elaborates on this by defining ecoregions as: "areas within which there is spatial coincidence in characteristics of geographical phenomena associated with differences in the quality and integrity of ecosystems". "Characteristics of geographical phenomena" may include geology, vegetation, hydrology and aquatic fauna, soils, may or may not include the impacts of human activity. There is significant, but not absolute, spatial correlation among these characteristics, making the delineation of ecoregions an imperfect science.
Another complication is that environmental conditions across an ecoregion boundary may change gradually, e.g. the prairie-forest transition in the midwestern United States, making it difficult to identify an exact dividing boundary. Such transition zones are called ecotones. Ecoregions can be categorized using an algorithmic approach or a holistic, "weight-of-evidence" approach where the importance of various factors may vary. An example of the algorithmic approach is Robert Bailey's work for the U. S. Forest Service, which uses a hierarchical classification that first divides land areas into large regions based on climatic factors, subdivides these regions, based first on dominant potential vegetation, by geomorphology and soil characteristics; the weight-of-evidence approach is exemplified by James Omernik's work for the United States Environmental Protection Agency, subsequently adopted for North America by the Commission for Environmental Cooperation. The intended purpose of ecoregion delineation may affect the method used.
For example, the WWF ecoregions were developed to aid in biodiversity conservation planning, place a greater emphasis than the Omernik or Bailey systems on floral and faunal differences between regions. The WWF classification defines an ecoregion as: A large area of land or water that contains a geographically distinct assemblage of natural communities that: Share a large majority of their species and ecological dynamics. According to WWF, the boundaries of an ecoregion approximate the original extent of the natural communities prior to any major recent disruptions or changes. WWF has identified 867 terrestrial ecoregions, 450 freshwater ecoregions across the Earth; the use of the term ecoregion is an outgrowth of a surge of interest in ecosystems and their functioning. In particular, there is awareness of issues relating to spatial scale in the study and management of landscapes, it is recognized that interlinked ecosystems combine to form a whole, "greater than the sum of its parts". There are many attempts to respond to ecosystems in an integrated way to achieve "multi-functional" landscapes, various interest groups from agricultural researchers to conservationists are using the "ecoregion" as a unit of analysis.
The "Global 200" is the list of ecoregions identified by WWF as priorities for conservation. Ecologically based movements like bioregionalism maintain that ecoregions, rather than arbitrarily defined political boundaries, provide a better foundation for the formation and governance of human communities, have proposed ecoregions and watersheds as the basis for bioregional democracy initiatives. Terrestrial ecoregions are land ecoregions, as distinct from marine ecoregions. In this context, terrestrial is used to mean "of land", rather than the more general sense "of Earth". WWF ecologists divide the land surface of the Earth into 8 major ecozones containing 867 smaller terrestrial ecoregions; the WWF effort is a synthesis of