Asimina tetramera
Encyclopedia
Asimina tetramera, commonly known as the four-petal pawpaw, is a species of flowering plant endemic to the state of Florida
. It is a small tree
or large perennial shrub
with one or more main stems. There is a total population count of about 950 plants, all of which are limited to areas in Martin
and Palm Beach Counties
in Florida. This is a federally listed endangered species
of the United States.
The branching brown, reddish, or grayish stems reach 1 to 3 meters in height. It is the tallest American pawpaw. The leaves are up to 10 centimeters long, green above and gray-green on the undersides, often with rolled edges. The flower is pink to maroon in color, changing color as it ages, and has a fetid scent. It has usually four sepal
s and six petals. The fruit is a yellow-green, banana-scented aggregate.
The plant has a sturdy underground root crown
that survives cold temperatures and wildfire
. It is a fire-adapted species which grows at faster rates and produces plentiful flowers and fruits in the seasons following a burn. If aboveground parts are burned away the plant resprouts. This is a species of the understory
which declines as other plants grow up around it and eventually shade it out. When fire comes through and burns away the surrounding vegetation, the pawpaw thrives. It is very long-lived, probably living well over a century, and able to spend much of its time in a dormant state underground before sprouting again.
The fruit provides food for many animals, including gopher tortoises, raccoon
s, and many rodent
s, including beach mice
. The flowers are pollinated
by beetle
s, and several types of fly
are attracted to the rotten scent. The zebra swallowtail butterfly
(Eurytides marcellus) lays its eggs on the leaves and the larva
e consume the leaves and flowers.
This plant occurs in Florida scrub
alongside sand pine (Pinus clausa), saw palmetto (Serenoa repens), and several types of oak
(Quercus spp.).
This rare plant is threatened by a number of forces. It depends on periodic natural fires to clear away the trees and brush that have taken over its habitat; fire suppression reduces its number and reduces the growth of individuals already present. Too much fire, however, can reduce the cover vegetation that is home to rodents which help disperse
the seeds. Habitat is lost to development and habitat fragmentation
has reduced the genetic variability
of the already small number of individuals. Pesticides, including those used for mosquito
control, may have reduced the numbers of pollinating insects.
Of the seventeen known occurrences of the plant, ten are on protected land, and several are on private land with no protection. The plant grows in Jonathan Dickinson State Park
, where the habitat is stewarded with controlled burn
s every six years.
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
. It is a small tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
or large perennial shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
with one or more main stems. There is a total population count of about 950 plants, all of which are limited to areas in Martin
Martin County, Florida
Martin County is a county in the U.S. state of Florida. As of 2000, the population was 126,731. The U.S. Census Bureau 2008 estimate for the county is 138,660. Its county seat is Stuart, Florida.- History :...
and Palm Beach Counties
Palm Beach County, Florida
Palm Beach County is the largest county in the state of Florida in total area, and third in population. As of 2010, the county's estimated population was 1,320,134, making it the twenty-eighth most populous in the United States...
in Florida. This 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.
The branching brown, reddish, or grayish stems reach 1 to 3 meters in height. It is the tallest American pawpaw. The leaves are up to 10 centimeters long, green above and gray-green on the undersides, often with rolled edges. The flower is pink to maroon in color, changing color as it ages, and has a fetid scent. It has usually four 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 and six petals. The fruit is a yellow-green, banana-scented aggregate.
The plant has a sturdy underground root crown
Root crown
A root crown is that part of a root system from which a stem arises. Since roots and stems have quite different vascular anatomies, major vascular changes take place at this point....
that survives cold temperatures and wildfire
Wildfire
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...
. It is a fire-adapted species which grows at faster rates and produces plentiful flowers and fruits in the seasons following a burn. If aboveground parts are burned away the plant resprouts. This is a species of the understory
Understory
Understory is the term for the area of a forest which grows at the lowest height level below the forest canopy. Plants in the understory consist of a mixture of seedlings and saplings of canopy trees together with understory shrubs and herbs...
which declines as other plants grow up around it and eventually shade it out. When fire comes through and burns away the surrounding vegetation, the pawpaw thrives. It is very long-lived, probably living well over a century, and able to spend much of its time in a dormant state underground before sprouting again.
The fruit provides food for many animals, including gopher tortoises, raccoon
Raccoon
Procyon is a genus of nocturnal mammals, comprising three species commonly known as raccoons, in the family Procyonidae. The most familiar species, the common raccoon , is often known simply as "the" raccoon, as the two other raccoon species in the genus are native only to the tropics and are...
s, and many rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s, including beach mice
Oldfield Mouse
The oldfield mouse or beach mouse is a nocturnal species of rodent in the family Cricetidae. It is found in the southeastern United States on sandy beaches, in corn and cotton fields, and in hedge rows and open timber tracts...
. 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 beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s, and several types of fly
Fly
True flies are insects of the order Diptera . They possess a pair of wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax...
are attracted to the rotten scent. The zebra swallowtail butterfly
Zebra Swallowtail Butterfly
The Zebra Swallowtail is a swallowtail butterfly native to the eastern United States and southeast Canada. Its distinctive wing shape and long tails make it easy to identify, and its black and white-striped pattern is reminiscent of a zebra...
(Eurytides marcellus) lays its eggs on the leaves and the larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e consume the leaves and flowers.
This plant occurs in Florida scrub
Florida scrub
Florida scrub is an endangered temperate coniferous forest ecoregion of the state of Florida in the United States. It is found on coastal and inland sand ridges and is characterized by a xeromorphic plant community dominated by shrubs and dwarf oaks. Scrub soils, a type of entisol, are derived...
alongside sand pine (Pinus clausa), saw palmetto (Serenoa repens), and several types of oak
Oak
An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...
(Quercus spp.).
This rare plant is threatened by a number of forces. It depends on periodic natural fires to clear away the trees and brush that have taken over its habitat; fire suppression reduces its number and reduces the growth of individuals already present. Too much fire, however, can reduce the cover vegetation that is home to rodents which help disperse
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...
the seeds. Habitat is lost to development and habitat fragmentation
Habitat fragmentation
Habitat fragmentation as the name implies, describes the emergence of discontinuities in an organism's preferred environment , causing population fragmentation...
has reduced the genetic variability
Genetic variability
Genetic variability is a measure of the tendency of individual genotypes in a population to vary from one another. Variability is different from genetic diversity, which is the amount of variation seen in a particular population. The variability of a trait describes how much that trait tends to...
of the already small number of individuals. Pesticides, including those used for mosquito
Mosquito
Mosquitoes are members of a family of nematocerid flies: the Culicidae . The word Mosquito is from the Spanish and Portuguese for little fly...
control, may have reduced the numbers of pollinating insects.
Of the seventeen known occurrences of the plant, ten are on protected land, and several are on private land with no protection. The plant grows in Jonathan Dickinson State Park
Jonathan Dickinson State Park
Jonathan Dickinson State Park is a Florida State Park and historic site located in Martin County, Florida, between Hobe Sound and Tequesta. The park includes a variety of natural communities, such as sand pine scrub, pine flatwoods, mangroves, and river swamps. The Loxahatchee River, which was...
, where the habitat is stewarded with controlled burn
Controlled burn
Controlled or prescribed burning, also known as hazard reduction burning or Swailing is a technique sometimes used in forest management, farming, prairie restoration or greenhouse gas abatement. Fire is a natural part of both forest and grassland ecology and controlled fire can be a tool for...
s every six years.