A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat regions covered with wind-swept sand or dunes, with little or no vegetation, are called ergs or sand seas. Dunes occur in different shapes and sizes, but most kinds of dunes are longer on the stoss (upflow) side, where the sand is pushed up the dune, and have a shorter slip face in the lee side. The valley or trough between dunes is called a dune slack.
The Namib is a coastal desert in Southern Africa. According to the broadest definition, the Namib stretches for more than 2,000 kilometres (1,200 mi) along the Atlantic coasts of Angola, Namibia, and northwest South Africa, extending southward from the Carunjamba River in Angola, through Namibia and to the Olifants River in Western Cape, South Africa. The Namib's northernmost portion, which extends 450 kilometres (280 mi) from the Angola-Namibia border, is known as Moçâmedes Desert, while its southern portion approaches the neighboring Kalahari Desert. From the Atlantic coast eastward, the Namib gradually ascends in elevation, reaching up to 200 kilometres (120 mi) inland to the foot of the Great Escarpment. Annual precipitation ranges from 2 millimetres (0.079 in) in the aridest regions to 200 millimetres (7.9 in) at the escarpment, making the Namib the only true desert in southern Africa. Having endured arid or semi-arid conditions for roughly 55–80 million years, the Namib may be the oldest desert in the world and contains some of the world's driest regions, with only western South America's Atacama Desert to challenge it for age and aridity benchmarks.
The Gran Desierto de Altar is one of the major sub-ecoregions of the Sonoran Desert, located in the State of Sonora, in northwest Mexico. It includes the only active erg dune region in North America. The desert extends across much of the northern border of the Gulf of California, spanning more than 100 kilometres (62 mi) east to west and over 50 kilometres (31 mi) north to south. It constitutes the largest continuous wilderness area within the Sonoran Desert.
Lennooideae is a subfamily of parasitic flowering plants of southwestern North America and northwestern South America.
Erysimum teretifolium is a species of Erysimum known by the common names Santa Cruz wallflower and Ben Lomond wallflower. It is a very rare plant endemic to Santa Cruz County, California, where it grows on inland sand spits, chaparral, and sandstone deposits in the southern Santa Cruz Mountains. It is a California state and federally listed endangered species.
A desert is a landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the land surface of the Earth is arid or semi-arid. This includes much of the polar regions, where little precipitation occurs, and which are sometimes called polar deserts or "cold deserts". Deserts can be classified by the amount of precipitation that falls, by the temperature that prevails, by the causes of desertification or by their geographical location.
Chorizanthe pungens is a species of flowering plant in the buckwheat family known by the common name Monterey spineflower. It is endemic to California, where it is known from the San Francisco Bay Area south along the Central Coast.
Eriogonum deserticola is a species of wild buckwheat known by the common name Colorado Desert buckwheat.
Monardella undulata subsp. crispa, synonym Monardella crispa is a rare subspecies of flowering plant in the mint family known by the common name crisp monardella. It is endemic to California, where it is known only from the sand dunes on the coastline of San Luis Obispo and Santa Barbara Counties.
Monardella undulata subsp. undulata, synonym Monardella frutescens, is a rare subspecies of flowering plant in the mint family known by the common name San Luis Obispo monardella.
Oenothera californica, known by the common name California evening primrose, is a species of flowering plant in the evening primrose family.
Penstemon albomarginatus is a rare species of penstemon known by the common name white-margined penstemon. It is native to the deserts of southern Nevada, western Arizona, and southern California.
Pholisma arenarium is a species of flowering plant in the borage family known by several common names, including desert Christmas tree, scaly-stemmed sand plant, and purple sand food. As the name implies, the loaf-like part of the root is edible. It is native to northwestern Mexico, Arizona and southern California, where it grows in many habitat types, including desert, chaparral, and sandy coastal dunes. It is a fleshy perennial herb taking a compact cylindrical or ovate shape up to 20 or 30 centimeters tall above ground, often with part of the stem below the sandy surface. It is a parasitic plant growing on the roots or of various shrubs such as burrobush, Yerba Santa, California croton, rabbitbrush, and ragweeds. As a heterotroph which derives its nutrients from other plants, it lacks chlorophyll and is brownish-gray or whitish in color. There are hairy, glandular, pointed leaves along the surface of the plant. Flowers emerge between them, each roughly one centimeter wide, the rounded corolla lavender to deep or bright purple with a white margin.
Bonnie Carolyn Templeton was an American botanist. She served as curator of botany for the Natural History Museum of Los Angeles County from 1929 to 1970, a time when women in science were uncommon.
Asclepias welshii is a rare species of milkweed known by the common name Welsh's milkweed. It is native to southern Utah and northern Arizona, where there are four known occurrences remaining. Most of the plants occur in Coral Pink Sand Dunes State Park, where the habitat has been degraded in many areas by off-road vehicle use. It is a federally listed threatened species of the United States.
Cardamine micranthera is a rare species of flowering plant in the mustard family known by the common names small-anthered bittercress and streambank bittercress. It is endemic to the Piedmont region around the border between Virginia and North Carolina, and is today restricted to the Dan River watershed. It is in decline mainly because its habitat has been disturbed and destroyed by a number of processes. By the 1960s the only known populations of the plant had disappeared and in the 1970s it was feared extinct. The plant was rediscovered in the 1980s and for a while was presumed to be a rare North Carolina endemic; populations in Virginia have been confirmed since. The plant was federally listed as an endangered species in 1989 when it was known from only four tiny populations on unprotected private land. Today there are about 32 occurrences; one occurrence in North Carolina has been extirpated and five others there had no specimens found at the most recent survey.
Dicerandra christmanii is a rare species of flowering plant in the mint family known by the common names Garrett's mint, yellow scrub balm, and Lake Wales balm. It is endemic to Highlands County, Florida, in the United States, where it is known from only four sites on the Lake Wales Ridge. All are contained within a tract of land measuring 6 kilometers by 3 kilometers. The plant is steadily declining due to the destruction and degradation of its habitat, and only one of the four occurrences is on protected land. It is a federally listed endangered species.
Dicerandra immaculata is a rare species of flowering plant in the mint family known by the common names Lakela's mint, Olga's mint, and spotless balm. It is endemic to Florida in the United States, where it is known only from Indian River and St. Lucie counties. There are seven occurrences of the plant, two of which are scheduled for destruction as the land is cleared for development. The plant was federally listed as an endangered species in 1985.
Penstemon acuminatus is a species of flowering plant in the plantain family known by the common names sharpleaf penstemon and sand-dune penstemon. It is native to the dry interior of the northwestern United States.
Flora of the Colorado Desert, located in Southern California. The Colorado Desert is a sub-region in the Sonoran Desert ecoregion of southwestern North America. It is also known as the Low Desert, in contrast to the higher elevation Mojave Desert or High Desert, to its north.
