Florida Fishpoison Tree

 Piscidia piscupula, the Florida fish poison tree, Jamaica dogwood, or fishfuddle tree, is a tropical hardwood native to south Florida and the Keys, the West Indies, Bahamas, and parts of Central America and Mexico. It is semi-deciduous, ie - shedding its leaves quickly, remaining bare only for a short time  before pushing out new growth. Flowers appear on bare or nearly bare stalks. It hit its flowering peak in the last week of May, and first week of June this year. 

Piscidia piscipula in bloom; 
edge of Johnson Bay, Isles of Capri, FL

The name "Jamaica dogwood" refers to its use in boat building. South Florida naturalist Roger Hammer reports that "dogs" are spikes or bars used as fasteners in ship construction. The flowers certainly don't look anything like the dogwoods most North Americans know. The wood is very  hard and apart from boats, is used for wood carving, fence posts and charcoal. 

Flowers

Typical "pea" flowers are borne in elongated clusters (racemes), and appear before, and sometimes overlapping with the year's new growth. Under magnification, they are hairy, especially the cup-like calyx, which appears to be a soft grayed lavender, like a mole's skin, due to the tiny hairs. Parts of the flower itself also bear silky hairs that are pressed flat on their surface. Flower color can vary quite a bit, from white tinged with pink or lavender, to red, to muddy gray. Like other members in the family, they attract a lot of pollinators, especially bees.

The bark and leaves contain rotenone, among other chemicals, and when tossed in the water, stun small fish, which float to the surface and can be harvested, hence the name "fishpoison." This practice is illegal in Florida, though we've reached such a state of general ignorance that I doubt anybody under 60 even knows the trick. 

Rotenone supposedly doesn't harm warm-blooded animals, but the plant contains plenty of other substances that do. Dried root bark is used  both internally and externally in folk medicine to relieve pain and insomnia to the point of unconsciousness, and to treat nervous disorders and skin ailments, but the plant's toxic/medicinal potential remains largely uninvestigated. Dried extract is available on the Internet, but I don't plan to play lab rat myself! For one thing, there seem to be no generally accepted dosage guidelines, but plenty of warnings.

The tree, which can reach 30-50 feet tall, with a broad, spreading crown, can make a striking specimen where it is not crowded. In shade and  competition from other plants it stays pretty spindly and unimpressive.  Osorio calls it "underutilized" in the Florida landscape. A sucking insect, the Jamaica Dogwood Psylla, occasionally can make the leaves unsightly, but again, acccording to Roger Hammer, doesn't make it undesirable in the landscape. It is highly drought tolerant once established, and grows behind the dune line on beaches, and in sand, rocky or gravelly soil elsewhere. Rather than falling over in storms, it tends to lose branches. 

Multi-trunked specimen,
Parking Lot, Collier-Seminole State Park
Collier County, FL

What first may appear to be leaves are actually leaflets. Like other members of the family, the fishpoison tree has compound leaves. They alternate along the branch, and typically have 4-8 pairs of leaflets plus a single terminal leaflet. The leaflets can vary in shape from more or less oblong to more oval, and the tips can be blunt, rounded or even pointed. They are fairly leathery on  top, and hairs  can give the underside a velvety feel. The leaves appear near the end of the flowering period. Leaves and individiual leaflets in the subfamily Faboidae, to which Piscidia piscipula belongs, are characterized by a swollen structure where they join the petiole or stem, called the "pulvinus." The leaves are a dark, matte green on top, and a lighter, softer shade on the underside. Varying pressure levels within the pulvinus cause the leaves and leaflets to fold up, seemingly at nighttime, but studies have shown that this is a biological rhythm not triggered by light levels. 

Piscidia
3 Mature Leaves; 3 Emerging Leaves

Members of Faboideae also are associated with the famous "nitrogen-fixing" bacteria, varioius species of Rhizobium. These symbiotic soil organisms "infect" root hairs of certain plants, especially members of Faboideae, where they transform atmospheric nitrogen into an ammonium form that can be used by the plant to produce plant protein. In turn, the bacteria gain carbohydrates from the host plant. Usually each Rhizobium species is limited to a single host species. Such complexity is probably one reason supposed "restoration" projects may fail, for replanting alone is a pretty simplistic approach. 

Black seeds are borne in a papery winged structure that passes from pink, green, yellow to brown. The tree apparently will grow readily from seed, as well as cuttings, so readily, in fact, that limbs used for fence posts make take root!

Seed Pods

The native Cassius Blue butterfly and the black and silver Hammock Skipper use the leaves as larval hosts. 

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I have relied heavily on the following sources for this article:

Roger Hammer. Florida Keys Wildflowers. Falcon. 2004. p.177. Email conversation.

Rufino Osorio. A Gardener's Guide to Florida Native Plants. University Press of Florida. 2001. pp. 265-6.

J. Paul Scurlock. Native Trees & Shrubs of the Florida Keys. Laurel Press. 1987, p. 123.

Wendy B. Zomlefer. Guide to Flowering Plant Families. University of North Carolina Press. 1994. pp. 160-166.