Aeschynomene virginica
Encyclopedia
Aeschynomene virginica is a rare species of flowering plant in the legume family
known by the common names Virginia jointvetch and sensitive jointvetch. It is native to a small section of the East Coast of the United States, where it has a fluctuating annual global population scattered in about 20 mostly small occurrences. Counts and estimates revealed two populations in New Jersey
including several thousand individuals, one population of a few hundred plants in Maryland
, several variable and unstable populations in ditches in North Carolina
, and several populations including about 5000 individuals in Virginia
. Habitat alteration has reduced the amount of sites where the plant can grow. The plant became a federally listed threatened species of the United States in 1992.
Some confusion has occurred in the literature, specifically that this species is named as a noxious weed of soybean
and rice fields
. The weedy species in question is actually Aeschynomene indica, not the rare and threatened A. virginica.
A. virginica is an annual herb which grows erect and can reach two meters in height. The alternately arranged leaves are each made up of many pairs of hairy, glandular leaflets. The leaves are touch-sensitive, folding when touched. Blooming takes place in summer and early fall. The pea-like flower is about a centimeter long and yellow in color with stark red veining. The flowers are pollinated
by insects such as the Least Skipper
(Ancylozypha numitor) and leaf-cutter bees
(family Megachilidae). The fruit is a legume pod up to 7 centimeters long which is narrowed between the seeds and easily segments. The segments float and the seeds may be dispersed
on the water if they don't fall out immediately. Bits of the pods may get caught up in floating vegetation debris and can be deposited with it in new territory.
This plant occurs in freshwater
tidal marsh
es that experience tidal action
but low salinity
. It grows in bare, disturbed areas that are mostly cleared of other vegetation, such as newly deposited shorelines or recently disturbed terrain dug out by muskrat
s. It germinates
in wet soils but not in submerged areas, and it is not successful in areas with thick vegetation. Despite its ability to take hold in tidally disturbed habitat it cannot withstand severe disturbance, such as patterns of increased sediment
ation, and human activity such as development, pollution
, or erosion
from boat wakes
.
Fabaceae
The Fabaceae or Leguminosae, commonly known as the legume, pea, or bean family, is a large and economically important family of flowering plants. The group is the third largest land plant family, behind only the Orchidaceae and Asteraceae, with 730 genera and over 19,400 species...
known by the common names Virginia jointvetch and sensitive jointvetch. It is native to a small section of the East Coast of the United States, where it has a fluctuating annual global population scattered in about 20 mostly small occurrences. Counts and estimates revealed two populations in New Jersey
New Jersey
New Jersey is a state in the Northeastern and Middle Atlantic regions of the United States. , its population was 8,791,894. It is bordered on the north and east by the state of New York, on the southeast and south by the Atlantic Ocean, on the west by Pennsylvania and on the southwest by Delaware...
including several thousand individuals, one population of a few hundred plants in Maryland
Maryland
Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...
, several variable and unstable populations in ditches in 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...
, and several populations including about 5000 individuals in 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...
. Habitat alteration has reduced the amount of sites where the plant can grow. The plant became a federally listed threatened species of the United States in 1992.
Some confusion has occurred in the literature, specifically that this species is named as a noxious weed of soybean
Soybean
The soybean or soya bean is a species of legume native to East Asia, widely grown for its edible bean which has numerous uses...
and rice fields
Paddy field
A paddy field is a flooded parcel of arable land used for growing rice and other semiaquatic crops. Paddy fields are a typical feature of rice farming in east, south and southeast Asia. Paddies can be built into steep hillsides as terraces and adjacent to depressed or steeply sloped features such...
. The weedy species in question is actually Aeschynomene indica, not the rare and threatened A. virginica.
A. virginica is an annual herb which grows erect and can reach two meters in height. The alternately arranged leaves are each made up of many pairs of hairy, glandular leaflets. The leaves are touch-sensitive, folding when touched. Blooming takes place in summer and early fall. The pea-like flower is about a centimeter long and yellow in color with stark red veining. The flowers are pollinated
Pollination
Pollination is the process by which pollen is transferred in plants, thereby enabling fertilisation and sexual reproduction. Pollen grains transport the male gametes to where the female gamete are contained within the carpel; in gymnosperms the pollen is directly applied to the ovule itself...
by insects such as the Least Skipper
Ancyloxypha numitor
The Least Skipper is a North American butterfly in the family Hesperiidae. They have a weak, satyr-like flight.-Description:...
(Ancylozypha numitor) and leaf-cutter bees
Megachilidae
The Megachilidae are a cosmopolitan family of solitary bees whose pollen-carrying structure is restricted to the ventral surface of the abdomen...
(family Megachilidae). The fruit is a legume pod up to 7 centimeters long which is narrowed between the seeds and easily segments. The segments float and the seeds may be dispersed
Biological dispersal
Biological dispersal refers to species movement away from an existing population or away from the parent organism. Through simply moving from one habitat patch to another, the dispersal of an individual has consequences not only for individual fitness, but also for population dynamics, population...
on the water if they don't fall out immediately. Bits of the pods may get caught up in floating vegetation debris and can be deposited with it in new territory.
This plant occurs in freshwater
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...
tidal marsh
Tidal marsh
A tidal marsh is a type of marsh that is found along coasts and estuaries of which the flooding characteristics are determined by the tidal movement of the adjacent estuary, sea or ocean . According to the salinity of the flooding water, freshwater, brackish and saline tidal marshes are...
es that experience tidal action
Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
but low salinity
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
. It grows in bare, disturbed areas that are mostly cleared of other vegetation, such as newly deposited shorelines or recently disturbed terrain dug out by muskrat
Muskrat
The muskrat , the only species in genus Ondatra, is a medium-sized semi-aquatic rodent native to North America, and introduced in parts of Europe, Asia, and South America. The muskrat is found in wetlands and is a very successful animal over a wide range of climates and habitats...
s. It germinates
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...
in wet soils but not in submerged areas, and it is not successful in areas with thick vegetation. Despite its ability to take hold in tidally disturbed habitat it cannot withstand severe disturbance, such as patterns of increased sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
ation, and human activity such as development, pollution
Pollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
, or erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
from boat wakes
Wake
A wake is the region of recirculating flow immediately behind a moving or stationary solid body, caused by the flow of surrounding fluid around the body.-Fluid dynamics:...
.