Astragalus microcymbus

Last updated

Astragalus microcymbus
Astragalus microcymbus.jpg
Status TNC G1.svg
Critically Imperiled  (NatureServe) [1]
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Fabales
Family: Fabaceae
Subfamily: Faboideae
Genus: Astragalus
Species:
A. microcymbus
Binomial name
Astragalus microcymbus
Barneby

Astragalus microcymbus is a species of flowering plant in the legume family known by the common name skiff milkvetch. It is endemic to Colorado in the United States, where it is known from Gunnison County and the edge of Saguache County. [2] It was discovered in 1945 by Rupert Barneby, [3] a British botanist.  Currently, skiff milkvetch is experiencing population declines and is listed as a Tier 1 species in the Rare Plant Addendum to the Colorado State Wildlife Action Plan. [4]

Contents

Description

The skiff milkvetch is a perennial herb native to Colorado. It has a lifespan ranging from 1–14 years with most individuals living for 2 to 3 years. Skiff milkvetch belongs to the Astragalus genus, the largest genus in the legume family, containing over 3,000 plant species. This genus is characterized by pinnately compound leaves and flowers growing in clusters referred to as racemes. The skiff milkvetch has loosely packed racemes, containing 7-14 flowers. [5] Flowers are pale-purple to off white, blooming from May to early July. The upper petal is notched and the lower petals have a purple tip. Leaves are 2–4 cm long with individual leaflets 3–9 mm long. [5] The common name "skiff" refers to the boat-shaped fruits produced by the plant. [6] Fruits are produced from late May through July, growing up to 8 mm long. [5] It is able to produce seeds in the first year of establishment and can continue reproduction for ten years, however, it is able to go dormant for multiple years at a time. [7] It is unknown if the plant is reliant on pollinators for reproduction, although findings suggest pollinators may play some role in seed production. [6] Seed dispersal is likely done via wind and rain, however this is not well researched. Skiff milkvetch has been observed using a mast seeding strategy, where whole populations produce excess seeds during some years and minimal seeds during other years. Skiff milkvetch stems exhibit a slight purple tinge and grow 2.5–6 centimetres (0.98–2.36 in) long between nodules, with the full plant growing up to 30 centimetres (12 in) tall; however, stems often grow along the ground or wrapped in other nearby vegetation.

Habitat

Range

The skiff milkvetch occupies a very small range within Gunnison County and likely into the northwestern edge of Saguache county within Southwestern Colorado. Historically, estimates have been up to 20,500 individual plants in five distinct populations. It is found in a 3.5-by-10-mile (5.6 km × 16.1 km) area with a disconnected population 10.5 miles (16.9 km) to the southwest.  These ranges occupy two distinct drainages: the South Beaver Creek drainage and the Cebolla Creek drainage, with elevation ranging from 2400 to 2500m. [7] These areas are land managed by the BLM (Bureau of Land Management) and private land owners. Skiff milkvetch live primarily on gravelly sandy loam soils that are well drained. Occasionally, they be found growing on rock outcroppings, loose stones, and shallow soils within sagebrush. [8] This region is relatively cold and dry, receiving about 20 inches (510 mm) of precipitation annually and having an average temperature of 39.1 °F (3.9 °C).[ citation needed ]

Ecology

Skiff milkvetch lives in the sagebrush steppe in the Mountain-Prairie region of the United States. [9] This region occupies the interior of the continent west of the Rocky Mountains. It is characterized by the dominant vegetation type, Sagebrush (Artemesia spp.). Living among the sagebrush are a variety of bird species, small mammals, predatory animals, and grazers. Most notably, there is the Gunnison sage-grouse, rabbit, coyote, and pronghorn. There are also a variety of herbaceous plants living in the understory of the sagebrush such as; native bromes, cacti, and other wildflowers with bitterbrush and rabbitbrush bushes. The skiff milkvetch provides a food source for small mammals that feed on the above ground vegetative structures of the plant.

Threats

Skiff milkvetch populations have been declining due to a variety of threats. Habitat loss is likely a source for declining populations. There has been an increase in urban development in Gunnison County near the habitat of skiff milkvetch. This habitat is only 2 to 7 miles (3.2 to 11.3 km) from the city of Gunnison, the largest in all of Gunnison County. Along with many towns in the Rocky Mountains, Gunnison is experiencing rapid population growth. Increased human populations are directly correlated to increasing habitat fragmentation through the building of infrastructure and increased recreation. Much of the range of skiff milkvetch lies within the popular recreation area of Hartman Rocks. This area is heavily used by off-highway vehicles (OHV) and mountain bikes. [7] A quarter of skiff milkvetch populations are on privately owned land with development on it. In addition to habitat loss, nonnative invasive plants are a source for population decreases in skiff milkvetch. [6] Among the invasive plants impacting skiff milkvetch populations is cheatgrass. Over the course of the past century cheatgrass has becoming a dominant force in shaping sagebrush ecosystems. It has experienced population increases due to shifting wildfire activity, agriculture, and livestock use in the sagebrush ecosystem. [6] Due to cheatgrass' extreme ability to reproduce it heavily alters ecosystems and out competes native vegetation. [10] Deer, elk, and livestock use the same habitat occupied by skiff milkvetch. These large grazers will eat the plant further reducing populations and may also trample on plants, killing them. There is long standing research on the negative impacts of livestock on native vegetation in arid western ecosystems. These effects can likely be applied to our understanding of skiff milkvetch, although they have not been explicitly researched. [6]

Skiff milkvetch has long been subject to herbivory by small mammals. [6] One study found that 26% of all skiff milkvetch plants had damage from herbivores. [7] Another suggested that after two consecutive years of heavy predation a plant dies. This is most impactful in years with increased rabbit populations. [6]

Finally, skiff milkvetch population decreases can be attributed to climate change. This plant is extremely sensitive to precipitation changes. [7] During summer drought conditions the entire plant becomes dormant, halting all reproductive efforts. [7] Current climate projections for the region favor drier, warmer summers. [6] This increase in summer drought condition will result in a lack of reproduction and decreased recruitment of skiff milkvetch.

Conservation efforts

In 2010, the skiff milkvetch was petitioned to be added to the list of endangered species protected by the U.S. government. However, it was ruled to be warranted but there are higher priority species that must be listed first, currently it listed as a candidate species. [6] Since 1995 the Denver Botanic Gardens have been monitoring skiff milkvetch populations, collecting data used in a variety of studies. [11] On going studies are focused on understanding the life history and reproductive methods of skiff milkvetch. One study is using data collected from 2019 and 2010 using 150 plants characterizing pollinator visits, seed bank effectivity, and herbivory. [12] Another focused on environmental conditions impacts on skiff milkvetch reproduction as well as herbivore impacts on population dynamics. [7] A different study has looked into population genetics of skiff milkvetch, furthering our understanding of the evolution and speciation of skiff milkvetch. [13] The plant has also been listed by the BLM as a special status species, meaning all recreation, treatments, and restoration efforts in the range of skiff milkvetch must be done with the plant's best interest in mind. [6]

Related Research Articles

<span class="mw-page-title-main">Wildlife garden</span>

A wildlife garden is an environment created with the purpose to serve as a sustainable haven for surrounding wildlife. Wildlife gardens contain a variety of habitats that cater to native and local plants, birds, amphibians, reptiles, insects, mammals and so on, and are meant to sustain locally native flora and fauna. Other names this type of gardening goes by can vary, prominent ones being habitat, ecology, and conservation gardening.

<span class="mw-page-title-main">Gunnison grouse</span> Species of bird

The Gunnison grouse, Gunnison sage-grouse or lesser sage-grouse is a species of grouse endemic to the United States. It is similar to the closely related greater sage-grouse in appearance, but about a third smaller in size, with much thicker plumes behind the head; it also has a less elaborate courtship dance. It is restricted in range to southwestern Colorado and extreme southeastern Utah, with the largest population residing in the Gunnison Basin region in Colorado. Despite being native to a country where the avifauna is relatively well known, it was overlooked until the 1990s due to the similarities with the sage grouse, and only described as a new species in 2000—making it the first new avian species to be described from the USA since the 19th century. The description of C. minimus as a separate species is supported by a molecular study of genetic variation, showing that gene flow between the large-bodied and the small-bodied birds is absent.

<span class="mw-page-title-main">Great Basin Desert</span> Desert in the western United States

The Great Basin Desert is part of the Great Basin between the Sierra Nevada and the Wasatch Range. The desert is a geographical region that largely overlaps the Great Basin shrub steppe defined by the World Wildlife Fund, and the Central Basin and Range ecoregion defined by the U.S. Environmental Protection Agency and United States Geological Survey. It is a temperate desert with hot, dry summers and snowy winters. The desert spans large portions of Nevada and Utah, and extends into eastern California. The desert is one of the four biologically defined deserts in North America, in addition to the Mojave, Sonoran, and Chihuahuan Deserts.

<i>Bromus tectorum</i> Species of grass

Bromus tectorum, known as downy brome, drooping brome or cheatgrass, is a winter annual grass native to Europe, southwestern Asia, and northern Africa, but has become invasive in many other areas. It now is present in most of Europe, southern Russia, Japan, South Africa, Australia, New Zealand, Iceland, Greenland, North America and western Central Asia. In the eastern US B. tectorum is common along roadsides and as a crop weed, but usually does not dominate an ecosystem. It has become a dominant species in the Intermountain West and parts of Canada, and displays especially invasive behavior in the sagebrush steppe ecosystems where it has been listed as noxious weed. B. tectorum often enters the site in an area that has been disturbed, and then quickly expands into the surrounding area through its rapid growth and prolific seed production.

<span class="mw-page-title-main">Sagebrush steppe</span> Grassland ecosystem

Sagebrush steppe is a type of shrub-steppe, a plant community characterized by the presence of shrubs, and usually dominated by sagebrush, any of several species in the genus Artemisia. This ecosystem is found in the Intermountain West in the United States.

<span class="mw-page-title-main">Great Basin pocket mouse</span> Species of rodent

The Great Basin pocket mouse is a species of rodent in the family Heteromyidae. It is found in British Columbia in Canada and the western United States.

<i>Astragalus lentiginosus</i> Species of plant

Astragalus lentiginosus is a species of legume native to western North America where it grows in a range of habitats. Common names include spotted locoweed and freckled milkvetch. There are a great number of wild varieties. The flower and the fruit of an individual plant are generally needed to identify the specific variety.

<i>Astragalus brauntonii</i> Species of legume

Astragalus brauntonii is a rare species of milkvetch known by the common name Braunton's milkvetch. It is endemic to California, where it is known from fewer than 20 extant occurrences in the hills and mountains surrounding the Los Angeles Basin in Southern California. This is a federally listed endangered species in the United States.

<i>Astragalus inversus</i> Species of legume

Astragalus inversus is a species of milkvetch known by the common name Susanville milkvetch.

<i>Astragalus ampullarioides</i> Species of legume

Astragalus ampullarioides is a rare species of milkvetch known by the common name Shivwits milkvetch. It was previously classified as a variety of Astragalus eremiticus. It is endemic to Washington County, Utah, where it is known from only seven populations. Estimates of the total number of individuals range from 1000 to 4200. The species occurs in desert scrub and woodlands on the Chinle Formation. It is a federally listed endangered species.

<i>Astragalus holmgreniorum</i> Species of endangered plant

Astragalus holmgreniorum is a rare species of milkvetch known by the common names Holmgren milk-vetch and paradox milk-vetch. It is native to a tiny section of desert shrub woodland on the border between Utah and Arizona, in the far northern Mojave Desert. There are six populations remaining. It is a federally listed endangered species.

<i>Astragalus osterhoutii</i> Species of astragalus

Astragalus osterhoutii, or the Osterhout milkvetch or Kremmling milkvetch, is an endangered species of milkvetch, discovered and collected in 1905 at Sulfur Spring in Grand County Colorado by Colorado botanist George Everett Osterhout for which the plant was named. It is found in the U.S. state of Colorado, in a 13 kilometres (8.1 mi) radius near the town of Kremmling.

<i>Astragalus phoenix</i> Species of legume

Astragalus phoenix is a rare species of milkvetch known by the common name Ash Meadows milkvetch. It is endemic to Nye County, in southwestern Nevada.

<i>Penstemon penlandii</i> Species of flowering plant

Penstemon penlandii is a rare species of flowering plant in the plantain family known by the common names Penland penstemon and Penland's beardtongue. It is endemic to Colorado in the United States, where it is known only from a strip of land about five miles long in central Grand County. There are two occurrences totalling about 8600 individuals. This is a federally listed endangered species of the United States.

Astragalus tyghensis is a species of flowering plant in the legume family known by the common name Tygh Valley milkvetch. It is endemic to Oregon in the United States, where it is known only from the Tygh Valley of Wasco County.

Astragalus anisus is a species of flowering plant in the legume family known by the common name Gunnison milkvetch. It is endemic to Colorado in the United States, where it is limited to the Gunnison Basin of Gunnison and Saguache Counties.

<i>Astragalus molybdenus</i> Species of legume

Astragalus molybdenus is a species of flowering plant in the legume family known by the common names Leadville milkvetch and molybdenum milkvetch. It is endemic to Colorado in the United States. If the separate species Astragalus shultziorum and Astragalus lackschewitzii are included in A. molybdenum the range expands into Wyoming and Montana.

<i>Astragalus ripleyi</i> Species of legume

Astragalus ripleyi is a species of flowering plant in the legume family known by the common name Ripley's milkvetch. It is native to southern Colorado and northern New Mexico in the United States.

The Sagebrush Sea, also called the sagebrush steppe, is an ecosystem of the Great Basin that is primarily centered on the 27 species of sagebrush that grow from sea level to about 12,000 feet. This ecosystem is home to hundreds of species of both fauna and flora. It includes small mammals such as pygmy rabbits, reptiles such as the sagebrush lizard, birds such as the golden eagles, and countless other species that are solely found in this ecosystem. This ecosystem at one point occupied over 62 million hectares in the western United States and southwestern Canada. It currently only occupies about 56 percent of historic range and is continuing to decline due to several factors.

<i>Astragalus cibarius</i> Species of legume

Astragalus cibarius, commonly called the browse milkvetch, is a species of plant in the legume family.

References

  1. ↑ NatureServe (6 October 2023). "Astragalus microcymbus". NatureServe Network Biodiversity Location Data accessed through NatureServe Explorer. Arlington, Virginia: NatureServe. Retrieved 2023-10-14.
  2. ↑ Astragalus microcymbus. The Nature Conservancy.
  3. ↑ "Barneby, Rupert Charles (1911-2000) on JSTOR". plants.jstor.org. Retrieved 2023-04-23.
  4. ↑ "Colorado's 2015 State Wildlife Action Plan, Table 1, Colorado Plants of Greatest Conservation Need" (PDF). Colorado Parks & Wildlife. 2015. p. A-12. Retrieved 2023-10-14.
  5. 1 2 3 "Astragalus microcymbus SKIFF MILKVETCH" (PDF). Retrieved 2023-04-01.
  6. 1 2 3 4 5 6 7 8 9 10 "Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To List Astragalus microcymbus and Astragalus schmolliae as Endangered or Threatened; Proposed Rule" (PDF). Fish and Wildlife Service. 15 December 2010. Retrieved 2023-04-01.
  7. 1 2 3 4 5 6 7 DePrenger-Levin, Michelle E.; Neale, Jennifer M. Ramp; Grant, Thomas A.; Dawson, Carol; Baytok, Yasemin Ergüner (July 2013). "Life History and Demography of Astragalus microcymbus Barneby (Fabaceae)". Natural Areas Journal. 33 (3): 264–275. doi:10.3375/043.033.0305. S2CID   84937328.
  8. ↑ Hunter, W. R. (1975). Soil survey of Gunnison Area, Colorado, parts of Gunnison, Hinsdale, and Saguache Counties. Washington: U.S. Govt. Print Off..
  9. ↑ "Skiff milkvetch (Astragalus microcymbus)". ECOS Environmental Conservation Online System. 21 March 2018. Retrieved 2023-04-01.
  10. ↑ Knapp, Paul A (April 1996). "Cheatgrass (Bromus tectorum L) dominance in the Great Basin Desert". Global Environmental Change. 6 (1): 37–52. doi:10.1016/0959-3780(95)00112-3.
  11. ↑ "Demographic Monitoring of Astragalus microcymbus". Denver Botanic Gardens. Retrieved 2023-04-23.
  12. ↑ Taylor, Bronwyn (17 September 2020). Reproductive ecology of Astragalus microcymbus, The (Thesis). hdl:10217/233621.
  13. ↑ Orr, Emily Rose (2022). Population Genomic Analysis of the Rare, Narrow Endemic, Astragalus Microcymbus (Thesis).
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.