Asclepias meadii
Encyclopedia
Asclepias meadii is a rare species of milkweed
known by the common name Mead's milkweed. It is native to the American Midwest
, where it was probably once quite widespread in the tallgrass prairie
. Today much of the Midwest has been fragmented
and claimed for agriculture
, and the remaining prairie habitat is degraded.
The plant is a federally listed threatened species
due to this destruction of its habitat. Factors contributing to its rarity include mowing and plowing, erosion
, loss of a natural prairie fire regime
, pesticide
s directly applied or drifting from nearby agricultural operations, invasive plant species
, trampling by hikers
, loss of native insect pollinators
, and predation by a number of insect species.
and Illinois
, and populations have been reintroduced to Indiana
and Wisconsin
, where the plant had been extirpated
. There are also some populations in Kansas
and Iowa
, but few of these may last, especially in Kansas, where they occur on private hay fields
that are mowed frequently.
perennial herb with a waxy erect stem growing up to about 40 centimeters tall. Blue-green, herringbone-patterned
leaves occur in opposite pairs about the stem. The lance-shaped blades are smooth and sometimes wavy along the edges, and measure up to 8 centimeters long. The inflorescence
is a nodding umbel
of 6 to 23 fragrant flowers. Each flower has five petals up to a centimeter long which are green or purple-tinged when new and grow paler as they age. Behind them are five reflexed sepal
s. The flowers are nectar-rich and are pollinated by digger bees
(Anthophora spp.), bumble bees (Bombus spp.), and other bees. The fruit is a follicle
up to 8 centimeters long containing hairy seeds. The species is long-lived, taking at least four years to reach sexual maturity and living for several decades, possibly over a century.
by sprouting more stems from its rhizome. It also sometimes reproduces sexually
by producing seed. A reduction in genetic diversity
is a threat to the species, because human activity and other processes have favored vegetative reproduction, a cloning
of the plants that does not remix genes. Mowing chops off the flowers or immature fruits, preventing seed production. Fragmentation of the habitat reduces the number of nearby plants that can trade pollen and the likelihood of visits from common pollinating insects.
, and the suppression of such fires is detrimental. Fire may have a number of beneficial fire ecology
effects on the plant, including increases in leaf and flower production and in genetic diversity.
. This plant, like many other milkweeds, hosts the Monarch butterfly (Danaus plexippus).
Asclepias
Asclepias L. , the milkweeds, is a genus of herbaceous perennial, dicotyledonous plants that contains over 140 known species...
known by the common name Mead's milkweed. It is native to the American Midwest
Midwestern United States
The Midwestern United States is one of the four U.S. geographic regions defined by the United States Census Bureau, providing an official definition of the American Midwest....
, where it was probably once quite widespread in the tallgrass prairie
Tallgrass prairie
The tallgrass prairie is an ecosystem native to central North America, with fire as its primary periodic disturbance. In the past, tallgrass prairies covered a large portion of the American Midwest, just east of the Great Plains, and portions of the Canadian Prairies. They flourished in areas with...
. Today much of the Midwest has been fragmented
Habitat fragmentation
Habitat fragmentation as the name implies, describes the emergence of discontinuities in an organism's preferred environment , causing population fragmentation...
and claimed for agriculture
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...
, and the remaining prairie habitat is degraded.
The plant is a federally listed threatened species
Threatened species
Threatened species are any speciesg animals, plants, fungi, etc.) which are vulnerable to endangerment in the near future.The World Conservation Union is the foremost authority on threatened species, and treats threatened species not as a single category, but as a group of three categories,...
due to this destruction of its habitat. Factors contributing to its rarity include mowing and plowing, 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...
, loss of a natural prairie fire regime
Fire regime
A fire regime is the pattern, frequency and intensity of the bushfires and wildfires that prevails in an area. It is an integral part of fire ecology, and renewal for certain types of ecosystems. If fires are too frequent, plants may be killed before they have matured, or before they have set...
, pesticide
Pesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
s directly applied or drifting from nearby agricultural operations, 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....
, trampling by hikers
Hiking
Hiking is an outdoor activity which consists of walking in natural environments, often in mountainous or other scenic terrain. People often hike on hiking trails. It is such a popular activity that there are numerous hiking organizations worldwide. The health benefits of different types of hiking...
, loss of native insect pollinators
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...
, and predation by a number of insect species.
Distribution
The only naturally-occurring populations of the plant are located in MissouriMissouri
Missouri is a US state located in the Midwestern United States, bordered by Iowa, Illinois, Kentucky, Tennessee, Arkansas, Oklahoma, Kansas and Nebraska. With a 2010 population of 5,988,927, Missouri is the 18th most populous state in the nation and the fifth most populous in the Midwest. It...
and Illinois
Illinois
Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...
, and populations have been reintroduced to Indiana
Indiana
Indiana is a US state, admitted to the United States as the 19th on December 11, 1816. It is located in the Midwestern United States and Great Lakes Region. With 6,483,802 residents, the state is ranked 15th in population and 16th in population density. Indiana is ranked 38th in land area and is...
and Wisconsin
Wisconsin
Wisconsin is a U.S. state located in the north-central United States and is part of the Midwest. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michigan to the northeast, and Lake Superior to the north. Wisconsin's capital is...
, where the plant had been extirpated
Local extinction
Local extinction, also known as extirpation, is the condition of a species which ceases to exist in the chosen geographic area of study, though it still exists elsewhere...
. There are also some populations in Kansas
Kansas
Kansas is a US state located in the Midwestern United States. It is named after the Kansas River which flows through it, which in turn was named after the Kansa Native American tribe, which inhabited the area. The tribe's name is often said to mean "people of the wind" or "people of the south...
and Iowa
Iowa
Iowa is a state located in the Midwestern United States, an area often referred to as the "American Heartland". It derives its name from the Ioway people, one of the many American Indian tribes that occupied the state at the time of European exploration. Iowa was a part of the French colony of New...
, but few of these may last, especially in Kansas, where they occur on private hay fields
Hay
Hay is grass, legumes or other herbaceous plants that have been cut, dried, and stored for use as animal fodder, particularly for grazing livestock such as cattle, horses, goats, and sheep. Hay is also fed to pets such as rabbits and guinea pigs...
that are mowed frequently.
Description
This is a rhizomatousRhizome
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...
perennial herb with a waxy erect stem growing up to about 40 centimeters tall. Blue-green, herringbone-patterned
Herringbone pattern
The herringbone pattern is an arrangement of rectangles used for floor tilings and road pavement.The blocks can be rectangles or parallelograms...
leaves occur in opposite pairs about the stem. The lance-shaped blades are smooth and sometimes wavy along the edges, and measure up to 8 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 nodding umbel
Umbel
An umbel is an inflorescence which consists of a number of short flower stalks which are equal in length and spread from a common point, somewhat like umbrella ribs....
of 6 to 23 fragrant flowers. Each flower has five petals up to a centimeter long which are green or purple-tinged when new and grow paler as they age. Behind them are five reflexed sepal
Sepal
A sepal is a part of the flower of angiosperms . Collectively the sepals form the calyx, which is the outermost whorl of parts that form a flower. Usually green, sepals have the typical function of protecting the petals when the flower is in bud...
s. The flowers are nectar-rich and are pollinated by digger bees
Anthophora
The bee genus Anthophora is one of the largest in the family Apidae, with over 450 species worldwide in 14 different subgenera. They are most abundant and diverse in the Holarctic and African biogeographic regions. All species are solitary, though many nest in large aggregations...
(Anthophora spp.), bumble bees (Bombus spp.), and other bees. The fruit is a follicle
Follicle (fruit)
In botany, a follicle is a dry unilocular many-seeded fruit formed from one carpel and dehiscing by the ventral suture in order to release seeds, such as in larkspur, magnolia, banksia, peony and milkweed....
up to 8 centimeters long containing hairy seeds. The species is long-lived, taking at least four years to reach sexual maturity and living for several decades, possibly over a century.
Reproduction
The species often reproduces vegetativelyVegetative reproduction
Vegetative reproduction is a form of asexual reproduction in plants. It is a process by which new individuals arise without production of seeds or spores...
by sprouting more stems from its rhizome. It also sometimes reproduces sexually
Sexual reproduction
Sexual reproduction is the creation of a new organism by combining the genetic material of two organisms. There are two main processes during sexual reproduction; they are: meiosis, involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the...
by producing seed. A reduction in genetic diversity
Genetic diversity
Genetic diversity, the level of biodiversity, refers to the total number of genetic characteristics in the genetic makeup of a species. It is distinguished from genetic variability, which describes the tendency of genetic characteristics to vary....
is a threat to the species, because human activity and other processes have favored vegetative reproduction, a cloning
Cloning
Cloning in biology is the process of producing similar populations of genetically identical individuals that occurs in nature when organisms such as bacteria, insects or plants reproduce asexually. Cloning in biotechnology refers to processes used to create copies of DNA fragments , cells , or...
of the plants that does not remix genes. Mowing chops off the flowers or immature fruits, preventing seed production. Fragmentation of the habitat reduces the number of nearby plants that can trade pollen and the likelihood of visits from common pollinating insects.
Fire ecology
The plant is adapted to occasional prairie fireWildfire
A wildfire is any uncontrolled fire in combustible vegetation that occurs in the countryside or a wilderness area. Other names such as brush fire, bushfire, forest fire, desert fire, grass fire, hill fire, squirrel fire, vegetation fire, veldfire, and wilkjjofire may be used to describe the same...
, and the suppression of such fires is detrimental. Fire may have a number of beneficial fire ecology
Fire ecology
Fire ecology is concerned with the processes linking the natural incidence of fire in an ecosystem and the ecological effects of this fire. Many ecosystems, such as the North American prairie and chaparral ecosystems, and the South African savanna, have evolved with fire as a natural and necessary...
effects on the plant, including increases in leaf and flower production and in genetic diversity.
Insect ecology
Insect pests that eat the plant include the milkweed beetles Tetraopes femoratus and Tetraopes tetraophthalamus and the milkweed weevils Rhyssematus annectans and Rhyssematus lineaticollisRhyssomatus lineaticollis
Rhyssomatus lineaticollis is a species of weevil whose adults feed on the stems of the common milkweed, Asclepias syriaca. It is also destructive to the rare and threatened milkweed species Asclepias meadii.-References:...
. This plant, like many other milkweeds, hosts the Monarch butterfly (Danaus plexippus).