Spiranthes delitescens
Encyclopedia
Spiranthes delitescens is a rare species of orchid known by the common name Canelo Hills lady's tresses, reclusive lady's tresses, and Madrean lady's tresses. It is native to Arizona
in the United States, where there are only four occurrences. It is threatened by the loss and degradation of its habitat. It is a federally listed endangered species
of the United States.
This orchid was first collected in 1968 and described to science as a species in 1990. It produces an erect stem up to 50 centimeters tall. The narrow leaves are arranged around the lower part of the stem and are up to 18 centimeters long. The inflorescence
is a spiraling spike of flowers. The stem in the inflorescence is covered in glandular hairs. Each flower has curving white, cream, or yellow-tinged petals nearly one centimeter in length. Blooming occurs in July and August. This and other orchid species depend on mycorrhiza
e, soil-dwelling fungi species, to assist with germination
, and for nutrition.
This plant grows in cienega
s, a wetland
habitat type in an otherwise dry region in the southwestern United States
, at an elevation
around 1525 meters (5000 feet). Other plants in the habitat include a variety of grass
es, sedges
, spikerushes
, cat-tails
, and horse-tails. Cienegas are kept seasonally wet by springs
. Two of the cienegas occupied by the orchid are the O'Donnell and Turkey Creek Cienegas, located about 40 kilometers southeast of Tucson, Arizona
. The O'Donnell Cienega is owned by The Nature Conservancy
, and a permanent caretaker lives at the site. The other two occurrences are Babocomari Cienega and Sheehy Spring nearby. The orchid may also exist south of the border in Sonora, Mexico. It is difficult to estimate the orchid's abundance, because it spends most of its time in a dormant, or vegetative state, remaining hidden in the dense surrounding vegetation with few identifiable aboveground parts.
The main threat to the species is the loss and degradation of its habitat, caused in part by the invasion
of non-native plant species
and the overgrowth of native plants. The worst invasive species is Johnson grass (Sorghum halepense). The orchid grows naturally next to various species of horse-tail and other marsh plants, and when these plants become too dense the orchid cannot penetrate the layers of vegetation. Horse-tails also outcompete
the orchid. It is likely that fire suppression is a threat, as fires naturally thin competing vegetation. Grazing
of cattle and other livestock is a threat, though grazing has been eliminated in the most sensitive cienega sites in most locations. Changes in the hydrology
of these wetland sites is a threat to the habitat, which is still recovering from draining operations initiated over a century ago. Pumping of groundwater
reduces available water in the habitat.
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, where there are only four occurrences. It is threatened by the loss and degradation of its habitat. It is a federally listed endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
of the United States.
This orchid was first collected in 1968 and described to science as a species in 1990. It produces an erect stem up to 50 centimeters tall. The narrow leaves are arranged around the lower part of the stem and are up to 18 centimeters long. 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 a spiraling spike of flowers. The stem in the inflorescence is covered in glandular hairs. Each flower has curving white, cream, or yellow-tinged petals nearly one centimeter in length. Blooming occurs in July and August. This and other orchid species depend on mycorrhiza
Mycorrhiza
A mycorrhiza is a symbiotic association between a fungus and the roots of a vascular plant....
e, soil-dwelling fungi species, to assist with germination
Germination
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...
, and for nutrition.
This plant grows in cienega
Cienega
A cienega or cienaga is a Spanish Colonial term for a spring, that is in use in English in the southwestern United States. A cienega usually is a wet, marshy area at the foot of a mountain, in a canyon, or on the edge of a grassland where groundwater bubbles to the surface...
s, a wetland
Wetland
A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....
habitat type in an otherwise dry region in the southwestern United States
Southwestern United States
The Southwestern United States is a region defined in different ways by different sources. Broad definitions include nearly a quarter of the United States, including Arizona, California, Colorado, Nevada, New Mexico, Oklahoma, Texas and Utah...
, at an elevation
Elevation
The elevation of a geographic location is its height above a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface ....
around 1525 meters (5000 feet). Other plants in the habitat include a variety of grass
Grass
Grasses, or more technically graminoids, are monocotyledonous, usually herbaceous plants with narrow leaves growing from the base. They include the "true grasses", of the Poaceae family, as well as the sedges and the rushes . The true grasses include cereals, bamboo and the grasses of lawns ...
es, sedges
Cyperaceae
Cyperaceae are a family of monocotyledonous graminoid flowering plants known as sedges, which superficially resemble grasses or rushes. The family is large, with some 5,500 species described in about 109 genera. These species are widely distributed, with the centers of diversity for the group...
, spikerushes
Eleocharis
Eleocharis is a genus of 250 or more species of flowering plants in the sedge family, Cyperaceae. They are known commonly as spikerushes, although spikesedges is a more technically appropriate name and most scientists who study them in earnest refer to them as such...
, cat-tails
Typha
Typha is a genus of about eleven species of monocotyledonous flowering plants in the family Typhaceae. The genus has a largely Northern Hemisphere distribution, but is essentially cosmopolitan, being found in a variety of wetland habitats...
, and horse-tails. Cienegas are kept seasonally wet by springs
Spring (hydrosphere)
A spring—also known as a rising or resurgence—is a component of the hydrosphere. Specifically, it is any natural situation where water flows to the surface of the earth from underground...
. Two of the cienegas occupied by the orchid are the O'Donnell and Turkey Creek Cienegas, located about 40 kilometers southeast of Tucson, Arizona
Tucson, Arizona
Tucson is a city in and the county seat of Pima County, Arizona, United States. The city is located 118 miles southeast of Phoenix and 60 miles north of the U.S.-Mexico border. The 2010 United States Census puts the city's population at 520,116 with a metropolitan area population at 1,020,200...
. The O'Donnell Cienega is owned by The Nature Conservancy
The Nature Conservancy
The Nature Conservancy is a US charitable environmental organization that works to preserve the plants, animals, and natural communities that represent the diversity of life on Earth by protecting the lands and waters they need to survive....
, and a permanent caretaker lives at the site. The other two occurrences are Babocomari Cienega and Sheehy Spring nearby. The orchid may also exist south of the border in Sonora, Mexico. It is difficult to estimate the orchid's abundance, because it spends most of its time in a dormant, or vegetative state, remaining hidden in the dense surrounding vegetation with few identifiable aboveground parts.
The main threat to the species is the loss and degradation of its habitat, caused in part by the invasion
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
of non-native plant species
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
and the overgrowth of native plants. The worst invasive species is Johnson grass (Sorghum halepense). The orchid grows naturally next to various species of horse-tail and other marsh plants, and when these plants become too dense the orchid cannot penetrate the layers of vegetation. Horse-tails also outcompete
Competition (biology)
Competition is an interaction between organisms or species, in which the fitness of one is lowered by the presence of another. Limited supply of at least one resource used by both is required. Competition both within and between species is an important topic in ecology, especially community ecology...
the orchid. It is likely that fire suppression is a threat, as fires naturally thin competing vegetation. Grazing
Grazing
Grazing generally describes a type of feeding, in which a herbivore feeds on plants , and also on other multicellular autotrophs...
of cattle and other livestock is a threat, though grazing has been eliminated in the most sensitive cienega sites in most locations. Changes in the hydrology
Hydrology
Hydrology is the study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability...
of these wetland sites is a threat to the habitat, which is still recovering from draining operations initiated over a century ago. Pumping of groundwater
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
reduces available water in the habitat.
External links
- Spiranthes delitescens. Arizona Native Plant Society Fact Sheet.
- USDA Plants Profile