Erigeron rhizomatus
Encyclopedia
Erigeron rhizomatus is a rare species of flowering plant in the aster family
known by the common names Zuni fleabane and rhizome fleabane. It is native to western New Mexico
and eastern Arizona
in the United States. It is a federally listed threatened species.
The plant was thought to be a New Mexico endemic until 1999, when some plants were found over the border in Arizona. These are located in the Chuska Mountains
in the Navajo Nation
, and they occur in 15 populations that make up one metapopulation
. The two previously known metapopulations in New Mexico are composed of 24 populations in the Zuni
, Datil, and Sawtooth Mountains. These three metapopulations are geographically isolated from each other but are still similar in morphology
.
and large network of clumped, fibrous roots topped with a branching caudex
. It produces one or more erect, rough-haired stems up to about 45 centimeters in maximum height. The leaves are lance-shaped near the base of the plant and much narrower and linear in shape toward the top of the stem. The inflorescence
is usually a single flower head
at the end of the stem which is lined with white or purple-tinged ray florets each under a centimeter long.
-rich sandstone
substrates that originate in the Baca and Chinle Formation
s. It occurs in barren outcrops of eroding red or grayish rock that may have slopes of up to 40 degrees. Nearby plants include four-wing saltbush
(Atriplex canescens), mountain mahogany
(Cercocarpus montanus), rubber rabbitbrush (Ericameria nauseosa), oneseed juniper
(Juniperus monosperma), Colorado pinyon
(Pinus edulis), and Gambel oak (Quercus gambelii).
activity in its habitat. There is probably still uranium
in the area, as evidenced by large amounts of selenium in the soil, which often occurs with uranium. If the value of uranium increases and it becomes a target for mining, the activity could threaten the plant's habitat. One population of the plant also occurs in an area with potential for oil exploration activity. These are the only significant threats to the species at this time, but since it is a rare regional endemic known from specific habitat types it will stay on the endangered species list
for the time being.
Asteraceae
The Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...
known by the common names Zuni fleabane and rhizome fleabane. It is native to western New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...
and eastern Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
in the United States. It is a federally listed threatened species.
The plant was thought to be a New Mexico endemic until 1999, when some plants were found over the border in Arizona. These are located in the Chuska Mountains
Chuska mountains
The Chuska Mountains are an elongate range on the Colorado Plateau and within the Navajo Nation. The range is about 80 by 15 km , and it trends north-northwest and is crossed by the state line between Arizona and New Mexico. The highlands are a dissected plateau, with an average elevation of...
in the Navajo Nation
Navajo Nation
The Navajo Nation is a semi-autonomous Native American-governed territory covering , occupying all of northeastern Arizona, the southeastern portion of Utah, and northwestern New Mexico...
, and they occur in 15 populations that make up one metapopulation
Metapopulation
A metapopulation consists of a group of spatially separated populations of the same species which interact at some level. The term metapopulation was coined by Richard Levins in 1970 to describe a model of population dynamics of insect pests in agricultural fields, but the idea has been most...
. The two previously known metapopulations in New Mexico are composed of 24 populations in the Zuni
Zuni Mountains
The Zuni Mountains are a mountain range in Cibola County of northwestern New Mexico. The range is located largely in the Cibola National Forest, lying south of Interstate 40 from southeast of Gallup to southwest of Grants. The range is about sixty miles long and forty miles wide...
, Datil, and Sawtooth Mountains. These three metapopulations are geographically isolated from each other but are still similar in morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
.
Characteristics
This is a perennial herb with a rhizomeRhizome
In botany and dendrology, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes...
and large network of clumped, fibrous roots topped with a branching caudex
Caudex
A caudex is a form of stem morphology appearing as a thickened, short, perennial stem that is either underground or near ground level . It may be swollen for the purpose of water storage, especially in xerophytes...
. It produces one or more erect, rough-haired stems up to about 45 centimeters in maximum height. The leaves are lance-shaped near the base of the plant and much narrower and linear in shape toward the top of the stem. The inflorescence
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
is usually a single flower head
Head (botany)
The capitulum is considered the most derived form of inflorescence. Flower heads found outside Asteraceae show lesser degrees of specialization....
at the end of the stem which is lined with white or purple-tinged ray florets each under a centimeter long.
Habitat
This plant grows in seleniumSelenium
Selenium is a chemical element with atomic number 34, chemical symbol Se, and an atomic mass of 78.96. It is a nonmetal, whose properties are intermediate between those of adjacent chalcogen elements sulfur and tellurium...
-rich sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
substrates that originate in the Baca and Chinle Formation
Chinle Formation
The Chinle is a geologic formation that is spread across the U.S. states of northern Arizona, Nevada, Utah, western New Mexico, and western Colorado. The Chinle is controversially considered to be synonymous to the Dockum Group in eastern Colorado, eastern New Mexico, southwestern Kansas, the...
s. It occurs in barren outcrops of eroding red or grayish rock that may have slopes of up to 40 degrees. Nearby plants include four-wing saltbush
Atriplex canescens
Atriplex canescens, Chamiso, Chamiza, Four wing saltbush, Four-wing saltbush, and Fourwing saltbush, is a species of evergreen shrub in the Amaranthaceae family, which is native to the western and mid-western United States....
(Atriplex canescens), mountain mahogany
Cercocarpus montanus
Cercocarpus montanus is a species of shrub or small tree in the family Rosaceae. It is known by various common names, such as mountain mahogany, true mountain-mahogany, alder-leaf mountain-mahogany, and alder-leaf cercocarpus...
(Cercocarpus montanus), rubber rabbitbrush (Ericameria nauseosa), oneseed juniper
Juniperus monosperma
Juniperus monosperma is a species of juniper native to western North America, in the United States in Arizona, New Mexico, southern Colorado, western Oklahoma , and western Texas, and in Mexico in the extreme north of Chihuahua...
(Juniperus monosperma), Colorado pinyon
Colorado Pinyon
The Colorado Pinyon, Two-needle Pinyon, or Piñon Pine, ', is a pine in the pinyon pine group whose ancestor was a member of the Madro-Tertiary Flora and is native to the United States....
(Pinus edulis), and Gambel oak (Quercus gambelii).
Endangered status
When the plant was listed for federal protection it was potentially threatened by uranium miningUranium mining
Uranium mining is the process of extraction of uranium ore from the ground. The worldwide production of uranium in 2009 amounted to 50,572 tonnes, of which 27% was mined in Kazakhstan. Kazakhstan, Canada, and Australia are the top three producers and together account for 63% of world uranium...
activity in its habitat. There is probably still uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
in the area, as evidenced by large amounts of selenium in the soil, which often occurs with uranium. If the value of uranium increases and it becomes a target for mining, the activity could threaten the plant's habitat. One population of the plant also occurs in an area with potential for oil exploration activity. These are the only significant threats to the species at this time, but since it is a rare regional endemic known from specific habitat types it will stay on the endangered species list
Endangered Species Act
The Endangered Species Act of 1973 is one of the dozens of United States environmental laws passed in the 1970s. Signed into law by President Richard Nixon on December 28, 1973, it was designed to protect critically imperiled species from extinction as a "consequence of economic growth and...
for the time being.