Critically Imperiled (NatureServe)
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 sepals 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, raccoons, and many rodents, including beach mice. The flowers are pollinated by beetles, 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 larvae consume the leaves and flowers.
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 burns every six years.
- Smithsonian Marine Station Fort Pierce
- USFWS. Proposed endangered and threatened status for three Florida shrubs. Federal Register November 1, 1985.
- Center for Plant Conservation