The only state where you'll find four-petal pawpaw, Asiminia tetramer, is Florida, and the only two counties in Florida where you'll find it are Martin and Palm Beach.
This plant is extremely rare. So rare that the number of living plants have been counted. So rare that both the federal government and the state list four-petal pawpaw as endangered. The problem is that it exists only in the coastal sandpine ridges of the two counties, land that is also extremely rare these days in an undeveloped state. The only chance for the four-petal pawpaw's survival, really, is preservation of as much of this land as is practical.
Four-petal pawpaw is a member of the custard apple family (a more widespread member of the clan is the pondapple) and can grow to about 10 feet high.
It has a tough, deep taproot that allows it to survive – and to an extent thrive after – intense fires. It actually produces more flowers and more fruit after a fire than in years prior, probably because open ground provides opportunity for new plants to establish themselves. It will survive when it's overshadowed by other plants, but it puts more energy into growing bigger leaves need for photosynthesis and less into flowering and fruiting.
Four-petal pawpaw flowers in the spring, peaking in May and June, but continuing through the summer. The flowers are cream-colored on the outside and deep red at the center. They are also unpleasant smelling. The leaves grow alternately along the stem, are oblong in shape and fairly large. The fruit is a berry-like thing called a monocarpal: a single flower can produce as many as eight monocarpals and each monocarpal can have as many as nine seeds.