Cardamine micranthera
Encyclopedia
Cardamine micranthera is a rare species of flowering plant in the mustard family
known by the common names small-anthered bittercress and streambank bittercress. It is endemic to the Piedmont
region around the border between Virginia
and North Carolina
, particularly in the Dan River
watershed
. It is in decline mainly because its habitat has been disturbed and destroyed by a number of processes. By the 1960s the only known populations of the plant had disappeared and in the 1970s it was feared extinct
. The plant was rediscovered in the 1980s and for a while was presumed to be a rare North Carolina endemic; populations in Virginia have been confirmed since. The plant was federally listed as an endangered species
in 1989 when it was known from only four tiny populations on unprotected private land. Today there are at least 20 occurrences for a total global population of at least 20,000 individuals. These statistics do not include certain populations that have not been surveyed recently.
This is a perennial herb producing a slender, sometimes branching stem 20 to 40 centimeters tall. The leaves are alternately arranged and mostly simple, but the basal leaves may have small lobes. Each flower has four small white petals and stamen
s with tiny rounded anthers. The fruit is a silique
around a centimeter long. The plant may be distinguished from its relative Cardamine rotundifolia by its smaller, rounder anthers, smaller petals, and shorter fruits.
This plant occurs in moist and wet, shady areas near streams and in dim woodlands. This habitat around the North Carolina-Virginia border has been impacted by human activity such as conversion to pasture
s, agricultural fields
, and residential property. The land is also affected by surface runoff
and herbicide
drift from nearby agricultural operations, and trampled by livestock
. Wetland
s have been contained, diverted, and reshaped. Invasive plant species
such as Japanese honeysuckle
(Lonicera japonica) now occur in the area. Flooding and logging
have been listed as threats, as well.
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 names small-anthered bittercress and streambank bittercress. It is endemic to the Piedmont
Piedmont (United States)
The Piedmont is a plateau region located in the eastern United States between the Atlantic Coastal Plain and the main Appalachian Mountains, stretching from New Jersey in the north to central Alabama in the south. The Piedmont province is a physiographic province of the larger Appalachian division...
region around the border between Virginia
Virginia
The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...
and North Carolina
North Carolina
North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...
, particularly in the Dan River
Dan River
The Dan River flows in the U.S. states of North Carolina and Virginia. It originates in Patrick County, Virginia, and crosses the state border into Stokes County, North Carolina. It then flows into Rockingham County. From there it goes back into Virginia. It reenters North Carolina near the...
watershed
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...
. It is in decline mainly because its habitat has been disturbed and destroyed by a number of processes. By the 1960s the only known populations of the plant had disappeared and in the 1970s it was feared extinct
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...
. The plant was rediscovered in the 1980s and for a while was presumed to be a rare North Carolina endemic; populations in Virginia have been confirmed since. The plant was 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...
in 1989 when it was known from only four tiny populations on unprotected private land. Today there are at least 20 occurrences for a total global population of at least 20,000 individuals. These statistics do not include certain populations that have not been surveyed recently.
This is a perennial herb producing a slender, sometimes branching stem 20 to 40 centimeters tall. The leaves are alternately arranged and mostly simple, but the basal leaves may have small lobes. Each flower has four small white petals and stamen
Stamen
The stamen is the pollen producing reproductive organ of a flower...
s with tiny rounded anthers. The fruit is a 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...
around a centimeter long. The plant may be distinguished from its relative Cardamine rotundifolia by its smaller, rounder anthers, smaller petals, and shorter fruits.
This plant occurs in moist and wet, shady areas near streams and in dim woodlands. This habitat around the North Carolina-Virginia border has been impacted by human activity such as conversion to pasture
Pasture
Pasture is land used for grazing. Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, cattle, sheep or swine. The vegetation of tended pasture, forage, consists mainly of grasses, with an interspersion of legumes and other forbs...
s, agricultural fields
Field
-Places:* Field, British Columbia, Canada* Field, Minneapolis, Minnesota, United States* Field, Ontario, Canada* Field Island, Nunavut, Canada* Mount Field - Expanses of open ground :* Field...
, and residential property. The land is also affected by surface runoff
Surface runoff
Surface runoff is the water flow that occurs when soil is infiltrated to full capacity and excess water from rain, meltwater, or other sources flows over the land. This is a major component of the water cycle. Runoff that occurs on surfaces before reaching a channel is also called a nonpoint source...
and herbicide
Herbicide
Herbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant...
drift from nearby agricultural operations, and trampled by livestock
Livestock
Livestock refers to one or more domesticated animals raised in an agricultural setting to produce commodities such as food, fiber and labor. The term "livestock" as used in this article does not include poultry or farmed fish; however the inclusion of these, especially poultry, within the meaning...
. 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....
s have been contained, diverted, and reshaped. Invasive plant species
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....
such as Japanese honeysuckle
Japanese Honeysuckle
The Japanese Honeysuckle is a species of honeysuckle native to eastern Asia including China , Japan, and Korea. It is a twining vine able to climb up to high or more in trees, with opposite, simple oval leaves long and broad...
(Lonicera japonica) now occur in the area. Flooding and logging
Logging
Logging is the cutting, skidding, on-site processing, and loading of trees or logs onto trucks.In forestry, the term logging is sometimes used in a narrow sense concerning the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard...
have been listed as threats, as well.