Lesquerella perforata
Encyclopedia
Lesquerella perforata is a rare species of flowering plant in the mustard family
known by the common name Spring Creek bladderpod. It is endemic to Tennessee
in the United States, where it is known only from Wilson County. This very rare plant is threatened by the loss and degradation of its habitat
. It is federally listed as an endangered species
.
This is an annual herb growing mostly erect to a height of 10 to 15 centimeters. The leaves are auriculate (ear-shaped), up to 5 centimeters long by 1.5 wide, and have toothed or lobed edges. They are usually hairy. The flowers have white or lavender petals with a yellow tinge at the bases. The fruit is an inflated silique
drying to a papery texture and measuring about half a centimeter wide. This species is similar to Lesquerella stonensis, another Tennessee endemic, from which it differs only in the arrangement of hairs on its fruits.
This plant only grows in the Central Basin
of Tennessee, where there are 21 known occurrences in Wilson County. The occurrences are almost all located on the floodplain
s of two or three creek
s within a five-mile radius of Lebanon
. The plant is adapted to a regime of periodic flood
ing as the creeks swell. The scouring action of the floodwaters maintain a floodplain that is clear of perennial grass
es and large or woody vegetation that would otherwise take hold and compete with the bladderpod. Large sections of this floodplain region have been converted to agricultural
use, and the soil disturbance created by plowing has replaced the natural disturbance of flooding. Certain agricultural practices do not adversely affect the plant, such as delaying spring plowing until the time of year when the plant has finished its reproduction. The fruit is mature and splits to release seeds in late April and early May. Other practices, such as no-till farming
, do not favor the plant's growth because they do not produce the soil disturbance that it would require in nature. Plowing the soil during times of the year when this annual plant has not yet matured and set seed can prevent the species' propagation.
The floodplain soil is silty and overlies limestone
substrates. The habitat includes natural floodplains and farm land such as crop fields and pastures. Other plants in the area include Echinacea tennesseensis
, Juniperus virginiana
, Petalostemon gattingeri, Sporobolus vaginiflorus
, Dalea foliosa
, Arabis perstellata
ampla, Thuja occidentalis
, and Picea rubens.
The lack of disturbance in the habitat causes its degradation by allowing the encroachment of large vegetation that crowds out the annual plants. The habitat in this region is being destroyed outright, however, by other processes, particularly the development of residential, commercial, and industrial complexes and associated utilities such as water lines and sewers. The plant's range is on the outer fringe of the Nashville metropolitan area, which is undergoing rapid growth. These threats prompted the addition of this plant to the endangered species list of the US.
Brassicaceae
Brassicaceae, a medium sized and economically important family of flowering plants , are informally known as the mustards, mustard flowers, the crucifers or the cabbage family....
known by the common name Spring Creek bladderpod. It is endemic to Tennessee
Tennessee
Tennessee is a U.S. state located in the Southeastern United States. It has a population of 6,346,105, making it the nation's 17th-largest state by population, and covers , making it the 36th-largest by total land area...
in the United States, where it is known only from Wilson County. This very rare plant is threatened by the loss and degradation of its habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
. It is federally listed as an 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...
.
This is an annual herb growing mostly erect to a height of 10 to 15 centimeters. The leaves are auriculate (ear-shaped), up to 5 centimeters long by 1.5 wide, and have toothed or lobed edges. They are usually hairy. The flowers have white or lavender petals with a yellow tinge at the bases. The fruit is an inflated silique
Silique
A silique or siliqua is a fruit of 2 fused carpels with the length being more than three times the width. The outer walls of the ovary usually separate when ripe, leaving a persistent partition...
drying to a papery texture and measuring about half a centimeter wide. This species is similar to Lesquerella stonensis, another Tennessee endemic, from which it differs only in the arrangement of hairs on its fruits.
This plant only grows in the Central Basin
Nashville Basin
The Nashville Basin, also known as the Central Basin, is a term often used to describe the area surrounding Nashville, Tennessee. The Central Basin was caused by an uplifting known as the Nashville Dome. The Nashville Dome is evidenced by the underlying rock strata that all dip downwards away from...
of Tennessee, where there are 21 known occurrences in Wilson County. The occurrences are almost all located on the floodplain
Floodplain
A floodplain, or flood plain, is a flat or nearly flat land adjacent a stream or river that stretches from the banks of its channel to the base of the enclosing valley walls and experiences flooding during periods of high discharge...
s of two or three creek
Stream
A stream is a body of water with a current, confined within a bed and stream banks. Depending on its locale or certain characteristics, a stream may be referred to as a branch, brook, beck, burn, creek, "crick", gill , kill, lick, rill, river, syke, bayou, rivulet, streamage, wash, run or...
s within a five-mile radius of Lebanon
Lebanon, Tennessee
Lebanon is a city in Wilson County, Tennessee, in the United States. The population was 20,235 at the 2000 census. It serves as the county seat of Wilson County. Lebanon is located in middle Tennessee, approximately 25 miles east of downtown Nashville. Local residents have also called it...
. The plant is adapted to a regime of periodic flood
Flood
A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water...
ing as the creeks swell. The scouring action of the floodwaters maintain a floodplain that is clear of perennial 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 and large or woody vegetation that would otherwise take hold and compete with the bladderpod. Large sections of this floodplain region have been converted to agricultural
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
use, and the soil disturbance created by plowing has replaced the natural disturbance of flooding. Certain agricultural practices do not adversely affect the plant, such as delaying spring plowing until the time of year when the plant has finished its reproduction. The fruit is mature and splits to release seeds in late April and early May. Other practices, such as no-till farming
No-till farming
No-till farming is a way of growing crops from year to year without disturbing the soil through tillage. No-till is an agricultural technique which increases the amount of water and organic matter in the soil and decreases erosion...
, do not favor the plant's growth because they do not produce the soil disturbance that it would require in nature. Plowing the soil during times of the year when this annual plant has not yet matured and set seed can prevent the species' propagation.
The floodplain soil is silty and overlies limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
substrates. The habitat includes natural floodplains and farm land such as crop fields and pastures. Other plants in the area include Echinacea tennesseensis
Echinacea tennesseensis
Echinacea tennesseensis, also known as the Tennessee coneflower or Tennessee purple coneflower, is a flowering plant in the family Asteraceae, endemic to the cedar glades of the central portion of the U.S. state of Tennessee.-Description:...
, Juniperus virginiana
Juniperus virginiana
Juniperus virginiana is a species of juniper native to eastern North America, from southeastern Canada to the Gulf of Mexico, east of the Great Plains...
, Petalostemon gattingeri, Sporobolus vaginiflorus
Sporobolus vaginiflorus
Sporobolus vaginiflorus is a species of grass known by the common names poverty grass, poverty dropseed, and sheathed dropseed.-Distribution:...
, Dalea foliosa
Dalea foliosa
Dalea foliosa is a species of flowering plant in the legume family known by the common name leafy prairie clover. It is an endangered species in the United States, where it occurs in three states: Illinois, Tennessee, and Alabama. As of 1997 there were 51 occurrences, mostly within the state of...
, Arabis perstellata
Arabis perstellata
Arabis perstellata is a rare species of flowering plant in the mustard family known by the common names Braun's rockcress and Nevada rockcress. It is native to Kentucky and Tennessee, where it is known from perhaps 25 total populations. Most of the occurrences have few individuals, and all are...
ampla, Thuja occidentalis
Thuja occidentalis
Thuja occidentalis is an evergreen coniferous tree, in the cypress family Cupressaceae, which is widely cultivated for use as an ornamental plant known as American Arbor Vitae. The endemic occurrence of this species is a northeastern distribution in North America...
, and Picea rubens.
The lack of disturbance in the habitat causes its degradation by allowing the encroachment of large vegetation that crowds out the annual plants. The habitat in this region is being destroyed outright, however, by other processes, particularly the development of residential, commercial, and industrial complexes and associated utilities such as water lines and sewers. The plant's range is on the outer fringe of the Nashville metropolitan area, which is undergoing rapid growth. These threats prompted the addition of this plant to the endangered species list of the US.