Joshua tree | |
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In Joshua Tree National Park, California | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Monocots |
Order: | Asparagales |
Family: | Asparagaceae |
Subfamily: | Agavoideae |
Genus: | Yucca |
Species: | Y. brevifolia |
Binomial name | |
Yucca brevifolia | |
Natural range in the United States | |
Synonyms [3] | |
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Yucca brevifolia (also known as the Joshua tree, yucca palm, tree yucca, and palm tree yucca) is a plant species belonging to the genus Yucca . It is tree-like in habit, which is reflected in its common names. [4] [5] [6] [7]
This monocotyledonous tree is native to the arid Southwestern United States, specifically California, Arizona, Utah, and Nevada, and northwestern Mexico. [8] It is confined mostly to the Mojave Desert between 400 and 1,800 m (1,300 and 5,900 ft) elevation. It thrives in the open grasslands of Queen Valley and Lost Horse Valley in Joshua Tree National Park. Other regions with a large population of the trees can be found northeast of Kingman, Arizona, in Mohave County; and along U.S. 93 just south of the community of Meadview, Arizona a route which has been designated the Joshua Tree Parkway of Arizona. [9] The trees are also abundant in Saddleback Butte State Park 135 kilometres (85 miles) north of Downtown Los Angeles in Los Angeles County's Antelope Valley. [10] The common name, Joshua tree, is derived from Christian iconography.
The Joshua tree is called "hunuvat chiy'a" or "humwichawa" by the indigenous Cahuilla. [11] It is also called izote de desierto (Spanish, "desert dagger"). [12] It was first formally described in the botanical literature as Yucca brevifolia by George Engelmann in 1871 as part of the Geological Exploration of the 100th meridian (or "Wheeler Survey"). [13]
The name "Joshua tree" is commonly said to have been given by a group of Mormon settlers crossing the Mojave Desert in the mid-19th century: The tree's role in guiding them through the desert combined with its unique shape reminded them of a biblical story in which Joshua keeps his hands reached out for an extended period of time to enable the Israelites in their conquest of Canaan (Joshua 8:18–26). [11] [14] [15] Further, the shaggy leaves may have provided the appearance of a beard. [16] However, no direct or contemporary attestation of this origin exists, and the name Joshua tree is not recorded until after Mormon contact; [11] [17] moreover, the physical appearance of the Joshua tree more closely resembles a similar story told of Moses. [18]
Ranchers and miners who were contemporaneous with the Mormon immigrants used the trunks and branches as fencing and for fuel for ore-processing steam engines. [19]
In addition to the autonymic subspecies Y. b. subsp. brevifolia, two other subspecies have been described: [20] Y. b. subsp. herbertii (Webber's yucca or Herbert Joshua tree) and Y. b. subsp. jaegeriana (the Jaeger Joshua tree or Jaeger's Joshua tree or pygmae yucca), though both are sometimes treated as varieties [12] [21] [22] or forms. [23] Y.b. subsp. jaegeriana has also been treated as its own species. [24] [25] [26]
Joshua trees grow quickly for a desert species; new seedlings may grow at an average rate of 7.6 cm (3.0 in) per year in their first 10 years, then only about 3.8 cm (1.5 in) per year. [27] The trunk consists of thousands of small fibers and lacks annual growth rings, making determining the tree's age difficult. This tree has a top-heavy branch system, and a broad root system, with roots in one case found 11 m (36 ft) from the nearest Joshua tree. [4] If it survives the rigors of the desert, it can live for several hundred years. The tallest trees reach about 15 m (49 ft). New plants can grow from seed, but in some populations, new stems grow from underground rhizomes that spread out around the parent tree.
The evergreen leaves are dark green, linear, bayonet-shaped, 15 to 35 cm long, and 7 to 15 mm broad at the base, tapering to a sharp point; they are borne in a dense spiral arrangement at the apex of the stems. The leaf margins are white and serrated.
Flowers typically appear from February to late April, in panicles 30 to 55 cm tall and 30 to 38 cm broad, the individual flowers erect, 4 to 7 cm tall, with six creamy white to green tepals. The tepals are lanceolate and are fused to the middle. The fused pistils are 3 cm tall and the stigma cavity is surrounded by lobes. The semi-fleshy fruit that is produced is green-brown, elliptical, and contains many flat seeds. Joshua trees usually do not branch until after they bloom (though branching may also occur if the growing tip is destroyed by the yucca-boring weevil), and they do not bloom every year. Like most desert plants, their blooming depends on rainfall at the proper time. They also need a winter freeze before they bloom.
Once they bloom, the flowers are pollinated by the yucca moth ( Tegeticula synthetica ), which spreads pollen while laying eggs inside the flower. The larvae feed on the seeds, but enough seeds remain to reproduce. The Joshua tree is also able to actively abort ovaries in which too many eggs have been produced.
The Joshua tree is native to the southwestern United States (Arizona, California, Nevada, and Utah) and northwestern Mexico. [8] This range mostly coincides with the geographical reach of the Mojave Desert, [4] where it is considered one of the major indicator species for the desert. It occurs at elevations between 400 and 1,800 m (1,300 and 5,900 ft). [28]
External videos | |
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"Can a fire-ravaged forest of Joshua trees be restored?", Tien Nguyen, Knowable Magazine , March 4, 2022. |
Joshua trees are one of the species predicted to have their range reduced and shifted by climate change. [29] Concern remains that they will be eliminated from Joshua Tree National Park, with ecological research suggesting a high probability that their populations will be reduced by 90% of their current range by the end of the 21st century, [30] [31] [32] [33] thus fundamentally transforming the ecosystem of the park. Wildfires, invasive grasses and poor migration patterns for the trees' seeds are all additional factors in the species' imperilment. [33] As an example, approximately 13%—or more than 1.3 million Joshua trees—in one of the densest Joshua tree populations in the world in Mojave National Preserve were killed in the Dome Fire in August 2020. [34] Also, concern exists about the ability of the species to migrate to favorable climates due to the extinction of the giant Shasta ground sloth (Nothrotheriops shastensis) 13,000 years ago; ground sloth dung has been found to contain Joshua tree leaves, fruits, and seeds, suggesting that the sloths might have been key to the trees' dispersal. However, ground squirrels are very effective at moving the seeds long distances. [30] [31]
In March 2022, California Department of Fish and Wildlife conducted a status review of the Western Joshua Tree to determine whether to list the species as threatened under the California Endangered Species Act (CESA). [35] The study showed that the largest threat to Yucca brevifolia was wildfires, that wildfires were a threat to population density of prone areas but not to the limits of the range itself, that several population studies showed Yucca brevifolia was abundant, and that although the southern region of the species' range has been reduced, the trend is that the northern region has been expanding over the last 11,700 years as the North American ice cap melted, allowing the species to occupy its current range. The studies showing reduced population after fires used aerial photography to document populations which would underreport smaller and thus younger trees, as was noted in the review. The review concluded:
Based on the criteria described above, the best scientific information available to the Department at this time indicates that western Joshua tree is not in serious danger of becoming extinct throughout all, or a significant portion, of its range due to one or more causes, including loss of habitat, change in habitat, overexploitation, predation, competition, or disease, and is not likely to become an endangered species in the foreseeable future in the absence of special protection and management efforts required by CESA.
In February 2023, California governor Gavin Newsom's administration proposed a budget trailer bill The Western Joshua Tree Conservation Act to focus on protecting the climate-threatened species and permitting development in the Southern California desert. The legislation requires conservation plan for this and other species that may be threatened by climate change and would authorize the California Department of Fish and Wildlife to permit taking a western Joshua tree only under certain conditions. [36] The legislation requires a fee of up to $2500 for the removal, relocation or trimming of limbs of a Western Joshua tree, including dead trees and limbs. [37]
This bill was passed by California lawmakers in June 2023 [38] and went into effect on July 10, 2023. [39]
Different forms of the species are cultivated, including smaller plants native from the eastern part of the species range. These smaller plants grow 2.5 m tall and branch when about 1 m tall. [40] Red-shafted flickers make nests in the branches, which are later used by other birds. [41]
Prior to the twentieth century, Native Americans of the Mojave and western Sonoran Desert routinely used several parts of the Joshua tree as food and fiber (Cornett, J.W., 2018, Indian Uses of Desert Plants, Nature Trails Press, Palm Springs, CA). Leaf fibers were occasionally used to bind and manufacture sandals. Root sheaths were woven into baskets to add reddish-brown designs. Fruits were baked or boiled then eaten. Seeds were ground into flour and mixed with flour from other plant species. The flour was moistened with water and the resulting paste was kneaded into cakes and dried.
Yucca is a genus of perennial shrubs and trees in the family Asparagaceae, subfamily Agavoideae. Its 40–50 species are notable for their rosettes of evergreen, tough, sword-shaped leaves and large terminal panicles of white or whitish flowers. They are native to the Americas and the Caribbean in a wide range of habitats, from humid rainforest and wet subtropical ecosystems to the hot and dry (arid) deserts and savanna.
The Mojave Desert is a desert in the rain shadow of the southern Sierra Nevada mountains and Transverse Ranges in the Southwestern United States. Named for the indigenous Mohave people, it is located primarily in southeastern California and southwestern Nevada, with small portions extending into Arizona and Utah.
Arthur B. Ripley Desert Woodland State Park is a state park in the western Antelope Valley in Southern California. The park protects mature stands of Joshua trees and California juniper trees in their western Mojave Desert habitat.
Yucca baccata is a common species of yucca native to the deserts of the southwestern United States and northwestern Mexico, from southeastern California north to Utah, east to western Texas and south to Sonora and Chihuahua. It is also reported in the wild in Colombia.
Pinus monophylla, the single-leaf pinyon, is a pine in the pinyon pine group, native to North America. The range is in southernmost Idaho, western Utah, Arizona, southwest New Mexico, Nevada, eastern and southern California and northern Baja California.
Yucca schidigera, also known as the Mojave yucca or Spanish dagger, is a perennial plant in the asaparagus family native to the southwestern United States and northwestern Mexico. It is most common in the Mojave Desert, but also occurs extensively in the Sonoran Desert and west to the Pacific coast of southern California and Baja California.
Saddleback Butte State Park is a state park in the Antelope Valley of the western Mojave Desert, in Southern California. It is located east of Lancaster, north of the community of Lake Los Angeles, and south of Edwards in the unincorporated community of Hi Vista.
The Providence Mountains are found in the eastern Mojave Desert of San Bernardino County, California, U.S. The range reaches an elevation of 7,162 feet (2,183 m) at Edgar Peak and is home to the Mitchell Caverns Natural Preserve in the Providence Mountains State Recreation Area, and the Mojave National Preserve.
The Morongo Basin is an endorheic basin and valley region located in eastern San Bernardino County, in Southern California.
The Lower Colorado River Valley (LCRV) is the river region of the lower Colorado River of the southwestern United States in North America that rises in the Rocky Mountains and has its outlet at the Colorado River Delta in the northern Gulf of California in northwestern Mexico, between the states of Baja California and Sonora. This north–south stretch of the Colorado River forms the border between the U.S. states of California/Arizona and Nevada/Arizona, and between the Mexican states of Baja California/Sonora.
The Piper Mountain Wilderness is a federally designated wilderness area located in the White Mountains 20 miles (32 km) northeast of Big Pine, California in Inyo County, California.
Joshua Tree National Park is a national park of the United States in southeastern California, east of San Bernardino and Los Angeles and north of Palm Springs. It is named after the Joshua trees native to the Mojave Desert. Originally declared a national monument in 1936, Joshua Tree was redesignated as a national park in 1994 when the U.S. Congress passed the California Desert Protection Act. Encompassing a total of 795,156 acres – slightly larger than the state of Rhode Island – the park includes 429,690 acres of designated wilderness. Straddling San Bernardino and Riverside Counties, the park includes parts of two deserts, each an ecosystem whose characteristics are determined primarily by elevation: the higher Mojave Desert and the lower Colorado Desert. The Little San Bernardino Mountains traverse the southwest edge of the park.
The deserts of California are the distinct deserts that each have unique ecosystems and habitats. The deserts are home to a sociocultural and historical "Old West" collection of legends, districts, and communities, and they also form a popular tourism region of dramatic natural features and recreational development. Part of this region was even proposed to become a new county due to cultural, economic and geographic differences relative to the rest of the more urban region.
The Date Creek Mountains is a short, arid range in southwest Yavapai County, Arizona. Congress is on its southeast foothills, and Wickenburg lies 15 mi (24 km) southeast.
Acamptopappus sphaerocephalus is a species of flowering plant in the family Asteraceae known by the common name rayless goldenhead. It is native to the southwestern United States, where it occurs in southern California, southern Nevada, southern Utah, and Arizona.
Ericameria paniculata is a species of flowering plant in the sunflower family Asteraceae, native to the southwestern United States. It is an evergreen yellow-flowered desert shrub.
The Beaver Dam Wash National Conservation Area is a 63,500-acre (257 km2) United States National Conservation Area located in southwest Utah west of St. George along the borders with Arizona and Nevada. It is managed by the U.S. Bureau of Land Management as part of the National Landscape Conservation System, and was authorized in the Omnibus Public Land Management Act of 2009.
Tegeticula antithetica is a species of moth in the family Prodoxidae. It is found in the Mojave Desert of the North American southwest, specifically southern California, southern Nevada, southwestern Utah, and western Arizona.
Hilaria rigida is a species of clumping perennial grass that is widespread in California deserts. It is commonly known as big galleta. It is a monocot in the Hilaria genus of the grass family (Poaceae).
The Burns Piñon Ridge Reserve is a 303-acre nature reserve that is part of the University of California Natural Reserve System. It is located near Yucca Valley, California in San Bernardino County, California. Administered by UC Irvine, the reserve is owned by the University of California and managed for teaching and research.
An application to Mr. Frederick V. Coville, botanist of the Department of Agriculture, elicited the following response: 'The statement is often made that this name Joshua-tree was applied to Cleistoyucca brevifolia because it was this tree which led the Mormons through the desert. I have no means of knowing, however, whether this explanation is authentic or whether it was invented as an explanation of the name. It seems to me more likely that Joshua tree is a garbled Indian name' […] I asked Professor Marcus E. Jones, whose knowledge of the desert flora is unsurpassed, and who has had a long acquaintance with members of the Mormon church. In reply, he kindly wrote as follows: 'The Mormon church officials do not know exactly the origin of the term, but assume that it is from the wide-spreading arms (branches) that in the night remind of the time when in battle Joshua had his arms held up in order to win a battle. This I got from one of the twelve apostles of the Mormon church.' Plausible as this explanation is, its value is more or less shaken when one finds, as I did after looking up the family Bible, that it was Moses, not Joshua, who had his arms held up during the battle, while Joshua conducted the fighting (Ex. 17:8–13). There is, however, another account of a fight, which may be what the Mormon apostle had in mind. It is told in the book of Joshua 7:18–26 [sic].