A seed is an embryonic plant enclosed in a protective outer covering. The formation of the seed is part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosperm plants. Seeds are the product of the ripened ovule, after fertilization by pollen and some growth within the mother plant; the embryo is developed from the seed coat from the integuments of the ovule. Seeds have been an important development in the reproduction and success of gymnosperm and angiosperm plants, relative to more primitive plants such as ferns and liverworts, which do not have seeds and use water-dependent means to propagate themselves. Seed plants now dominate biological niches on land, from forests to grasslands both in hot and cold climates; the term "seed" has a general meaning that antedates the above – anything that can be sown, e.g. "seed" potatoes, "seeds" of corn or sunflower "seeds". In the case of sunflower and corn "seeds", what is sown is the seed enclosed in a shell or husk, whereas the potato is a tuber.
Many structures referred to as "seeds" are dry fruits. Plants producing berries are called baccate. Sunflower seeds are sometimes sold commercially while still enclosed within the hard wall of the fruit, which must be split open to reach the seed. Different groups of plants have other modifications, the so-called stone fruits have a hardened fruit layer fused to and surrounding the actual seed. Nuts are the one-seeded, hard-shelled fruit of some plants with an indehiscent seed, such as an acorn or hazelnut. Seeds are produced in several related groups of plants, their manner of production distinguishes the angiosperms from the gymnosperms. Angiosperm seeds are produced in a hard or fleshy structure called a fruit that encloses the seeds for protection in order to secure healthy growth; some fruits have layers of both fleshy material. In gymnosperms, no special structure develops to enclose the seeds, which begin their development "naked" on the bracts of cones. However, the seeds do become covered by the cone scales.
Seed production in natural plant populations varies from year to year in response to weather variables and diseases, internal cycles within the plants themselves. Over a 20-year period, for example, forests composed of loblolly pine and shortleaf pine produced from 0 to nearly 5 million sound pine seeds per hectare. Over this period, there were six bumper, five poor, nine good seed crops, when evaluated for production of adequate seedlings for natural forest reproduction. Angiosperm seeds consist of three genetically distinct constituents: the embryo formed from the zygote, the endosperm, triploid, the seed coat from tissue derived from the maternal tissue of the ovule. In angiosperms, the process of seed development begins with double fertilization, which involves the fusion of two male gametes with the egg cell and the central cell to form the primary endosperm and the zygote. Right after fertilization, the zygote is inactive, but the primary endosperm divides to form the endosperm tissue.
This tissue becomes the food the young plant will consume until the roots have developed after germination. After fertilization the ovules develop into the seeds; the ovule consists of a number of components: The funicle or seed stalk which attaches the ovule to the placenta and hence ovary or fruit wall, at the pericarp. The nucellus, the remnant of the megasporangium and main region of the ovule where the megagametophyte develops; the micropyle, a small pore or opening in the apex of the integument of the ovule where the pollen tube enters during the process of fertilization. The chalaza, the base of the ovule opposite the micropyle, where integument and nucellus are joined together; the shape of the ovules as they develop affects the final shape of the seeds. Plants produce ovules of four shapes: the most common shape is called anatropous, with a curved shape. Orthotropous ovules are straight with all the parts of the ovule lined up in a long row producing an uncurved seed. Campylotropous ovules have a curved megagametophyte giving the seed a tight "C" shape.
The last ovule shape is called amphitropous, where the ovule is inverted and turned back 90 degrees on its stalk. In the majority of flowering plants, the zygote's first division is transversely oriented in regards to the long axis, this establishes the polarity of the embryo; the upper or chalazal pole becomes the main area of growth of the embryo, while the lower or micropylar pole produces the stalk-like suspensor that attaches to the micropyle. The suspensor absorbs and manufactures nutrients from the endosperm that are used during the embryo's growth; the main components of the embryo are: The cotyledons, the seed leaves, attached to the embryonic axis. There may be two; the cotyledons are the source of nutrients in the non-endospermic dicotyledons, in which case they replace the endosperm, are thick and leathery. In endospermic seeds the cotyledons are papery. Dicotyledons have the point of attachment opposite one another on the axis; the epicotyl, the embryonic axis above the point of attachment of the cotyledon.
The plumule, the tip of the epicotyl, has a feathery appearance due to the presence of young leaf primordia at the apex, will become the shoot upon germination. The hypocotyl, the embryonic axis below the point of attachment of the cotyledon, connecting the epicotyl and the radicle, being the stem-root transition zone; the radicle, the basal tip of the hy
Natural landscaping called native gardening, is the use of native plants, including trees, shrubs and grasses which are indigenous to the geographic area of the garden. Natural landscaping is adapted to the climate and hydrology and should require no pesticides and watering to maintain, given that native plants have adapted and evolved to local conditions over thousands of years. However, these applications may be necessary for some preventive care of trees and other vegetation in areas of degraded or weedy landscapes. Native plants suit today's interest in "low-maintenance" gardening and landscaping, with many species vigorous and hardy and able to survive winter cold and summer heat. Once established, they can flourish without irrigation or fertilization, are resistant to most pests and diseases. Many municipalities have recognized the benefits of natural landscaping due to municipal budget constraints and reductions and the general public is now benefiting from the implementation of natural landscaping techniques to save water and create more personal time.
Native plants provide suitable habitat for native species of butterflies, birds and other wildlife. They provide more variety in gardens by offering myriad alternatives to the planted introduced species and invasive species; the indigenous plants have co-evolved with animals and microbes, to form a complex network of relationships. They are natural communities; such gardens benefit from the plants being evolved and habituated to the local climate and herbivores, soil conditions, so may require fewer to no soil amendments, irrigation and herbicides for a beautiful, lower maintenance, more sustainable landscape. However, while local provenance plants have adapted to local conditions, there will be instances in cities, where one or more of these will have been radically altered. Examples include: Building rubble used as landfill may raise soil pH, which can be problematic in regions of acidic soils. Buildings cast a substantial shade, this may give rise to conditions shadier than needed by local plants.
Soil, high in organic material and nutrients is introduced into gardens, or many gardeners will have used fertilizers. Plants from some areas may not thrive under these conditions. For example, many Australian plants are sensitive to phosphorus. Many native plants are adapted to, benefit from, periodic wildfires that occurred before and during pre-modern settlement; these fires can be simulated in the garden by either "high mowing" or a controlled burn every few years. Many weeds in an area are the result of imported plants; these plants become invasive because there are no natural controls such as disease, weather, or fauna in their new environment. They take over native habitats, reducing food for local fauna. Using local provenance plants increases the biodiversity of and is important for the health of a region's overall ecology. Much of the wild areas have been destroyed to make room for urban development. Housing developments have replaced native habitats with ornamental plants and lawns, pushing the wildland-urban interface further out.
While development won't be stopped, gardeners can keep wild areas and green spaces filled with native species on their lots and in their communities. Despite this, there are plenty of indigenous or native plants which will grow and thrive in the area one is trying to establish a native garden. Native gardens include the following kinds: Fully forested with leaf debris on the forest floor, including coarse woody debris if possible. "Wildflower" in some nations denominates the numerous showy flowers from some drier climates, most notably southwest Western Australia, southern Africa, North America. Some wildflower gardens attempt to recreate a prairie, including native grasses along with flowering plants, i. e. forbs. Such gardens benefit the local wildlife attracting birds and small mammals. By choosing the plants for the garden, some of these animals can be encouraged to visit the garden. One popular type of wildflower garden specializes in attracting butterflies and is thus denominated a "butterfly garden".
The native plants cultivated in wildflower gardens have deep roots, therefore are effective selections for absorbing surface runoff and allowing the water to infiltrate into the local water table. Wildflower gardens cultivated for capturing runoff in this mode are denominated "rain gardens". Rain gardens absorb rainwater from gutters & impervious surfaces and function much better when planted with native plants which tolerate the alternation of flooding and drying. No fertilization required no additional water more water available for other uses and other people zero to near zero work needed for maintenance no lawn mowing erosion reduced to a minimum natural landscaped plants take full advantage of rainfall when water restrictions are implemented, natural landscaped plants will survive, while more traditional plants may not increased habitat for native flora and fauna increased beneficial insect population reduces pests where forested, provides shade on homes and businesses saving energy native plants become invasive not good for outdoor games that require a manicured turf. in certain areas, wildfires or brush
The Mojave Desert is an arid rain-shadow desert and the driest desert in North America. It is in the southwestern United States within southeastern California and southern Nevada, it occupies 47,877 sq mi. Small areas extend into Utah and Arizona, its boundaries are noted by the presence of Joshua trees, which are native only to the Mojave Desert and are considered an indicator species, it is believed to support an additional 1,750 to 2,000 species of plants. The central part of the desert is sparsely populated, while its peripheries support large communities such as Las Vegas, Lancaster, Victorville, St. George; the Mojave Desert is bordered by the Great Basin Desert to its north and the Sonoran Desert to its south and east. Topographical boundaries include the Tehachapi Mountains to the west, the San Gabriel Mountains and San Bernardino Mountains to the south; the mountain boundaries are distinct because they are outlined by the two largest faults in California – the San Andreas and Garlock faults.
The Mojave Desert displays typical range topography. Higher elevations above 2,000 ft in the Mojave are referred to as the High Desert; the Mojave Desert occupies less than 50,000 sq mi, making it the smallest of the North American deserts. The Mojave Desert is referred to as the "high desert", in contrast to the "low desert", the Sonoran Desert to the south; the Mojave Desert, however, is lower than the Great Basin Desert to the north. The spelling Mojave originates from the Spanish language while the spelling Mohave comes from modern English. Both are used today, although the Mojave Tribal Nation uses the spelling Mojave; the Mojave Desert receives less than 2 inches of rain a year and is between 2,000 and 5,000 feet in elevation. The Mojave Desert contains the Mojave National Preserve, as well as the lowest and hottest place in North America: Death Valley at 282 ft below sea level, where the temperature surpasses 120 °F from late June to early August. Zion National Park in Utah lies at the junction of the Mojave, the Great Basin Desert, the Colorado Plateau.
Despite its aridity, the Mojave has long been a center of alfalfa production, fed by irrigation coming from groundwater and from the California Aqueduct. The Mojave is a desert of two distinct seasons. Winter months bring comfortable daytime temperatures, which drop to around 25 °F on valley floors, below 0 °F at the highest elevations. Storms moving from the Pacific Northwest can bring rain and in some places snow. More the rain shadow created by the Sierra Nevada as well as mountain ranges within the desert such as the Spring Mountains, bring only clouds and wind. In longer periods between storm systems, winter temperatures in valleys can approach 80 °F. Spring weather continues to be influenced by Pacific storms, but rainfall is more widespread and occurs less after April. By early June, it is rare for another Pacific storm to have a significant impact on the region's weather. Summer weather is dominated by heat. Temperatures on valley floors can soar above 130 °F at the lowest elevations. Low humidity, high temperatures, low pressure, draw in moisture from the Gulf of Mexico creating thunderstorms across the desert southwest known as the North American monsoon.
While the Mojave does not get nearly the amount of rainfall the Sonoran desert to the south receives, monsoonal moisture will create thunderstorms as far west as California's Central Valley from mid-June through early September. Autumn is pleasant, with one to two Pacific storm systems creating regional rain events. October is one of the sunniest months in the Mojave. After temperature, wind is the most significant weather phenomenon in the Mojave. Across the region windy days are common. During the June Gloom, cooler air can be pushed into the desert from Southern California. In Santa Ana wind events, hot air from the desert blows into the Los Angeles basin and other coastal areas. Wind farms in these areas generate power from these winds; the other major weather factor in the region is elevation. The highest peak within the Mojave is Charleston Peak at 11,918 feet, while the Badwater Basin in Death Valley is 279 feet below sea level. Accordingly and precipitation ranges wildly in all seasons across the region.
The Mojave Desert has not supported a fire regime because of low fuel loads and connectivity. However, in the last few decades, invasive annual plants such as some within the genera Bromus and Brassica have facilitated fire; this has altered many areas of the desert. At higher elevations, fire regimes are infrequent; the Mojave Desert is defined by numerous mountain ranges creating its xeric conditions. These ranges create valleys, endorheic basins, salt pans, seasonal saline lakes when precipitation is high enough. These
In biology, taxonomy is the science of defining and naming groups of biological organisms on the basis of shared characteristics. Organisms are grouped together into taxa and these groups are given a taxonomic rank; the principal ranks in modern use are domain, phylum, order, family and species. The Swedish botanist Carl Linnaeus is regarded as the founder of the current system of taxonomy, as he developed a system known as Linnaean taxonomy for categorizing organisms and binomial nomenclature for naming organisms. With the advent of such fields of study as phylogenetics and systematics, the Linnaean system has progressed to a system of modern biological classification based on the evolutionary relationships between organisms, both living and extinct; the exact definition of taxonomy varies from source to source, but the core of the discipline remains: the conception and classification of groups of organisms. As points of reference, recent definitions of taxonomy are presented below: Theory and practice of grouping individuals into species, arranging species into larger groups, giving those groups names, thus producing a classification.
A field of science that encompasses description, identification and classification The science of classification, in biology the arrangement of organisms into a classification "The science of classification as applied to living organisms, including study of means of formation of species, etc." "The analysis of an organism's characteristics for the purpose of classification" "Systematics studies phylogeny to provide a pattern that can be translated into the classification and names of the more inclusive field of taxonomy" The varied definitions either place taxonomy as a sub-area of systematics, invert that relationship, or appear to consider the two terms synonymous. There is some disagreement as to whether biological nomenclature is considered a part of taxonomy, or a part of systematics outside taxonomy. For example, definition 6 is paired with the following definition of systematics that places nomenclature outside taxonomy: Systematics: "The study of the identification and nomenclature of organisms, including the classification of living things with regard to their natural relationships and the study of variation and the evolution of taxa".
A whole set of terms including taxonomy, systematic biology, biosystematics, scientific classification, biological classification, phylogenetics have at times had overlapping meanings – sometimes the same, sometimes different, but always related and intersecting. The broadest meaning of "taxonomy" is used here; the term itself was introduced in 1813 by de Candolle, in his Théorie élémentaire de la botanique. A taxonomic revision or taxonomic review is a novel analysis of the variation patterns in a particular taxon; this analysis may be executed on the basis of any combination of the various available kinds of characters, such as morphological, palynological and genetic. A monograph or complete revision is a revision, comprehensive for a taxon for the information given at a particular time, for the entire world. Other revisions may be restricted in the sense that they may only use some of the available character sets or have a limited spatial scope. A revision results in a conformation of or new insights in the relationships between the subtaxa within the taxon under study, which may result in a change in the classification of these subtaxa, the identification of new subtaxa, or the merger of previous subtaxa.
The term "alpha taxonomy" is used today to refer to the discipline of finding and naming taxa species. In earlier literature, the term had a different meaning, referring to morphological taxonomy, the products of research through the end of the 19th century. William Bertram Turrill introduced the term "alpha taxonomy" in a series of papers published in 1935 and 1937 in which he discussed the philosophy and possible future directions of the discipline of taxonomy. … there is an increasing desire amongst taxonomists to consider their problems from wider viewpoints, to investigate the possibilities of closer co-operation with their cytological and genetical colleagues and to acknowledge that some revision or expansion of a drastic nature, of their aims and methods, may be desirable … Turrill has suggested that while accepting the older invaluable taxonomy, based on structure, conveniently designated "alpha", it is possible to glimpse a far-distant taxonomy built upon as wide a basis of morphological and physiological facts as possible, one in which "place is found for all observational and experimental data relating if indirectly, to the constitution, subdivision and behaviour of species and other taxonomic groups".
Ideals can, it may be said, never be realized. They have, however, a great value of acting as permanent stimulants, if we have some vague, ideal of an "omega" taxonomy we may progress a little way down the Greek alphabet; some of us please ourselves by thinking. Turrill thus explicitly excludes from alpha taxonomy various areas of study that he includes within taxonomy as a whole, such as ecology, physiology and cytology, he further excludes phylogenetic reconstruction from alp
The Transverse Ranges are a group of mountain ranges of southern California, in the Pacific Coast Ranges physiographic region in North America. The Transverse Ranges begin at the southern end of the California Coast Ranges and lie within Santa Barbara, Los Angeles, San Bernardino and Riverside counties; the Peninsular Ranges lie to the south. The name Transverse Ranges is due to their east–west orientation, making them transverse to the general northwest–southeast orientation of most of California's coastal mountains; the ranges extend from west of Point Conception eastward 500 kilometers into the Mojave and Colorado Desert. The geology and topography of the ranges express three distinct segments that have contrasting elevations, rock types, vegetation; the western segment extends to the San Gabriel Mountains and San Gabriel fault. The central segment includes; the eastern segment extends from the San Andreas fault eastward to the Colorado Desert. The central and eastern segments have the highest elevations.
Most of the ranges lie in the California chaparral and woodlands ecoregion. Lower elevations are dominated by chaparral and scrubland, while higher elevations support large conifer forests. Most of the ranges in the system are fault blocks, were uplifted by tectonic movements late in the Cenozoic Era. West of Tejon Pass, the primary rock types are varied, with a mix of sedimentary and metamorphic rocks, while regions east of the pass are dominated by plutonic granitic and metasedimentary rocks; the western and central segments of the Transverse Ranges are bounded to the north and east by the San Andreas Fault, which separates those segments from the Mojave Desert. The eastern segment bounds the southern Mojave Desert. Notable passes along the San Andreas fault include Tejon Pass, Cajon Pass, San Gorgonio Pass. Components of Transverse Ranges to the north and east of the fault include the San Bernardino Mountains, Little San Bernardino Mountains and Eagle Mountains; the western and southern boundaries are acknowledged to be the Pacific Ocean and the northern Channel Islands.
Onshore the Los Angeles Basin lies at the southern boundary of the western and central segments of the ranges. Major passes not along the San Andreas Fault include Gaviota Pass, San Marcos Pass, the Conejo Grade, Newhall Pass, Cahuenga Pass; the Transverse Ranges manifest themselves as a series of parallel ridges with an average height of 3,000–8,000 feet. The ranges are dissected by young, steep streams of low flow rate; the mountains are notable for being difficult to traverse. There are few passes that are sufficiently low or wide enough to accommodate significant volumes of traffic; this has resulted in situations where major cities are linked to the rest of the state by few roads. This results in significant traffic issues throughout Southern California when a pass has to be shut down due to heavy snow or construction. Major cities, such as Santa Barbara during the 2005 La Conchita landslide, may be cut off from timely road access to the rest of Southern California. Major peaks of the Transverse Ranges with at least 500 feet of prominence, listed by height: This segment begins at Point Conception in Santa Barbara County, include the Santa Ynez Mountains that run parallel to the coast behind Santa Barbara.
The western Transverse Ranges include the Topatopa Mountains and the Santa Susana Mountains of Ventura County and Los Angeles County, the Simi Hills, the Santa Monica Mountains that run along the Pacific coast behind Malibu, whose eastern portion are known as the Hollywood Hills, the Chalk Hills. The northern Channel Islands of California are part of the Transverse Ranges; the Ranges include the steep San Gabriel Mountains northeast of Los Angeles, the Verdugo Mountains, the Liebre-Sawmill Mountains, the San Rafael Hills, Puente Hills, San Jose Hills, Chino Hills. The San Bernardino Mountains, Little San Bernardino Mountains, the Pinto and Orocopia Mountains are within the eastern segment; the Mojave Desert and California's low desert, including the Coachella Valley, are at the eastern end of the ranges. Ranges north of the western segment that are nearly transverse but are part of the California Coast Ranges include the San Rafael Mountains and the Sierra Madre Mountains; the Tehachapi Mountains north of the Mojave Desert, although nearly transverse, are the southern end of the Sierra Nevada.
The climate in most of the range is Csb under the Köppen climate classification. Snow falls above 6,000 feet most winters, above 3,000 feet every few years, it is rare for elevations above 8,000 feet to go multiple winters without snow during severe droughts. Due to low humidity, the regional snow line lies at about 14,000–16,000 feet, above the highest elevation of the range.
Indigenous peoples of California
The indigenous peoples of California are the indigenous inhabitants who have lived or live in the geographic area within the current boundaries of California before and after the arrival of Europeans. With over forty groups seeking to be federally recognized tribes, California has the second largest Native American population in the United States; the California cultural area does not conform to the state of California's boundaries. Many tribes on the eastern border with Nevada are classified as Great Basin tribes, some tribes on the Oregon border are classified as Plateau tribes. Tribes in Baja California who do not cross into California are classified as indigenous peoples of Mexico. Before European contact, native Californians spoke over 300 dialects of 100 distinct languages; the large number of languages has been related to the ecological diversity of California, to a sociopolitical organization into small tribelets with a shared "ideology that defined language boundaries as unalterable natural features inherent in the land"."The majority of California Indian languages belong either to localized language families with two or three members or are language isolates."
Of the remainder, most are Athapaskan languages. Larger groupings have been proposed; the Hokan superstock has been most difficult to demonstrate. There is evidence suggestive that speakers of the Chumashan languages and Yukian languages, languages of southern Baja California such as Waikuri, were in California prior to the arrival of Penutian languages from the north and Uto-Aztecan from the east predating the Hokan languages. Wiyot and Yurok are distantly related to Algonquian languages in a larger grouping called Algic; the several Athapaskan languages are recent arrivals, no more recent than about 2000 years ago. Evidence of human occupation of California dates from at least 19,000 years ago. Prior to European contact, California Indians had 500 distinct sub-tribes or groups, each consisting of 50 to 500 individual members; the size of California tribes today are small compared to tribes in other regions of the United States. Prior to contact with Europeans, the California region contained the highest Native American population density north of what is now Mexico.
Because of the temperate climate and easy access to food sources one-third of all Native Americans in the United States were living in the area of California. Early Native Californians were hunter-gatherers, with seed collection becoming widespread around 9,000 BC. Due to the local abundance of food, tribes tilled the soil. Two early southern California cultural traditions include the La Jolla Complex and the Pauma Complex, both dating from ca. 6050—1000 BC. From 3000 to 2000 BC, regional diversity developed, with the peoples making fine-tuned adaptations to local environments. Traits recognizable to historic tribes were developed by 500 BC; the indigenous people practiced various forms of sophisticated forest gardening in the forests, mixed woodlands, wetlands to ensure availability of food and medicine plants. They controlled fire on a regional scale to create a low-intensity fire ecology. By burning underbrush and grass, the natives revitalized patches of land and provided fresh shoots to attract food animals.
A form of fire-stick farming was used to clear areas of old growth to encourage new in a repeated cycle. Different tribes encountered non-native European explorers and settlers at different times; the southern and central coastal tribes encountered Spanish and British explorers in the mid-16th century. Tribes such as the Quechan or Yuman Indians in present-day southeast California and southwest Arizona first encountered Spanish explorers in the 1760s and 1770s. Tribes on the coast of northwest California, like the Miwok and Yokut, had contact with Russian explorers and seafarers in the late 18th century. In remote interior regions, some tribes did not meet non-natives until the mid-19th century; the Spanish began their long-term occupation in California in 1769 with the founding of Mission San Diego de Alcalá in San Diego. The Spanish built 20 additional missions in California, their introduction of European invasive plant species and non-native diseases resulted in unintended havoc and high fatalities for the Native Californian tribes.
The population of Native California was reduced by 90% during the 19th century—from more than 200,000 in the early 19th century to 15,000 at the end of the century due to disease. Epidemics swept through California Indian Country, such as the 1833 malaria epidemic. Early to mid 19th Century, coastal tribes of northwest California had multiple contacts with Russian explorers due to Russian colonization of the Americas. At that time period, Russian exploration of California and contacts with local population were associated with the activity of the Russian-American Company. A Russian explorer, Baron Ferdinand von Wrangell, visited California in 1818, 1833, 1835. Looking for a potential site for a new outpost of the company in California in place of Fort Ross, Wrangell’s expedition encountered the Indians north of San Francisco Bay and visited their village. In his notes Wrangell remarked that local women, used to physical labor, seemed to be of stronger constitution than men, whose main activity was hunting.
Local provision consisted of fish and products made of seeds and grains: usually