Floridas Genera of Leguminous Trees

At least 40 of North America's indigenous trees are from the legume family, and a large assortment of nonnative varieties have been introduced for ornamental purposes. Of these, at least 24 species in 16 genera now occur in Florida. A large number of these are native to the state; a few, however, are naturalized plants that have escaped from cultivation and are often enjoyed for their showy flowers or edible fruit.

In addition to the 24 leguminous species referenced above, there are many more tree-sized legumes thai are used sinctlv as ornamentals. Most of these are found in the more tropical regions of southern Florida. Ii is likely that at least some of these species will eventually become established as components ot Florida's flora. However, the following discussion does not include these latter plants.

The family Leguminosae (also sometimes referred to as the Fabaceae) is so large that some botanists have divided it into a number of subfamilies, l'he Mimosoideae ts one of the largest of these subfamilies and is represented by a number of genera in Florida including the Acacia, Atbizia, Leucaena* Lysiloma, and Pitheceilabium.

The genus Acacia is one of the world's largest genera of flowering plants. Estimates suggest that the number of Acacia species may range from as few as 600 to over 11 iOO. The genus is composed primarily of trees and woody shrubs, mostly of the tropical, subtropical, and, to a lesser degree, warm-temperate regions of the world. Six members o! the genus are either native to or naturalized in Florida. However, many Acacia species, especially those from Australia* are cultivated in the southern portions of the stale for their fragrant and appealing flowers.

All of our Acacia have bipinnately compound leaves and, with the exception of the tamarindillo (A. choriapfryHa), all also have very small leaflets and spiny branches. Of the six species found in Florida, only two art widespread. The sweet acacia (A. fame* siana) and pine acacia (A. pinetorum) are both found widely across much of the southern peninsula and the Keys. Both occur primarily in hammocks and pinelands along the coastal zone and are easy to differentiate. The sweet acacia has leaflets longer than 3 nun. and the pine acacia has leaflets shorter than 3 mm. The other four Florida Acacia are either highly localized in distribution or relatively uncommon in the state.

The genus Albtzia is much smaller than the genus Acacia, Composed of approximately 100 species worldwide, it, too, is distributed primarily in the tropical and sulv

tropical regions of the uorld, Both of Florida's Alhizia species have been introduced to the state. The mimosa, or silk tree (A. julibrissin), is native to Asia from about Iran to China, Korea, and Japan but has been cultivated widely in the United Slates, It is quite common in the east from Washington, D.C., and Mary land southward to central Florida and west to Texas, Its attractive, bipinnate leaves, and delightful, pink and white cottony flowers are distinguishing field marks.

The woman's tongue (A. iebbeck), a close relative of the silk tree, is native to subtropical Asia. It has been introduced into southern Florida and has now become naturalized, Unlike the mimosa, its flowers are predominately creamy yellow - The two species are likely to be found together only in the central peninsula. They may be separated from each other by the silk tree's shorter leaflets and by the color of their flowers.

The lead tree, or jumbie bean (Leucaena leucocephala)( is a small, spreading tree that is typically found in pine lands and hammocks along ihe coastal ¿one from about Tampa southward. It is an exotic species, but some authors still treat it as possibly native. It has spread widely in southern Florida due primarily to cultivation. The seeds of the jumbie bean have been used to fashion bracelets, necklaces, and other such trinkets, and the foliage has been used for the production of fertilizer as well as feed for livestock. Live plants are used as shade trees for coffee and cacao.

Wild tamarind (Lysiloma laiisitiquum) is one of a small genus of about 35 species worldwide. It is a native plant and is a common component of several tropical hammocks of the upper Keys and Dade County, It is hardy, salt-tolerant, and has few natural enemies, ft is also known to invade the pine lands that surround many of south Florida's hammocks. Frank Craighead, in the introduction to volume one of his Trees of South ttorida, describes the wild tamarind as one of the more characteristic irees of the pine ridge hammock community.

Lysiloma latisiliquum is only one of two south Florida species referred to as tamarind. The other, Tamarindus indica, is a nonnative species that is cultivated in the state's southern counties. It probably originated in Africa but has been cultivated in India for many generations, hence its specific name. It is planted in lire breaks in India, but is best known for its tie shy, edible fruit that is often used in the production of candies, jellies, and beverages» as well as to spice up certain Indian recipes. T. indica is persistent in parts of southern Florida and can sometimes be seen along roadsides, especially near the coast

Three of Florida's native or naturalized legumes arc particularly noted for their ornamental value. Two of these are predominately tropical species and are found only in southern Florida, but one is common in the northern parts of the state.

I he eastern redhud (Cercis canadensis) is one of north Florida's best known native species. It is a delicately branched and attractive tree that is scattered over most of the eastern United States and is generally found on rich, moist sites from southern Canada to Florida and Texas, Its exquisitely colored flowers range from light pink to magenta and normally appear in early spring, before the tree puts out new leaves. Its blooms are so beautiful and appear in such profusion along the naked branches that the tree is often considered to produce one of the most spectacular splashes of early spring color.

LEGUMES

This factor alone explains why the tree is often found planted in yards and gardens, as well as alongside city streets.

In south Florida, the exotic orchid trees (Bauhinia variegata and B> purpurea) and royal poinciana (Detonix regia) rival the redbud in beauty and ornamental use. The former are common in the Miami area as we I! as the Keys, and are characterized by simple, two-ranked leaves with exquisite* purplish, orchidlike flowers. The flowers of B variegaia generally appear between January and March while the tree is leafless; those of B- purpurea appear more generally during the fall from about September to December, and the tree is more nearly evergreen. The two frees are difficult io distinguish and only the former species is included in Part II

The royal poinciana undoubtedly takes its common name from its regal, bright red, frilly-petaled flowers that appear from early to midsummer. It, loo, is a common ornamental that often decorates south Florida lawns. In addition to its showy flowers, it ex-hi bits giant puds to about 50 cm long that hang on the tree nearly all year. Hie roots of this species grow very close to the surface and are known to break up sidewalks. Even so, the royal poinciana is still commonly used as a street tree throughout southern Florida and the tropics.

Three trees in two genera bear the common name locust. Of these, the water-locust (Gieditsia aquatka) and honey-locust {G triacanthos) arc most similar. Both are native species with even-pinnate, or occasionally bipinnate, leaves with many leaflets. The most distinguishing characteristic of these trees are the numerous sharp thorns found along their trunks and branches. Sometimes borne singly, these stiff, strong, extremely sharp, needle-tipped appendages arc also often found in large masses along the lower trunk. The young, reddish colored thoms are also conspicuous among new leaf growth.

The water- and honey-locust are most readily differentiated by lheir fruits. The pods of the former are oval in shape and quite short, usually measuring less than 5 cm in length. Those of the honey-locust are much longer, ranging between 10 and 40 cm in overall length.

The black locust {Robinia pseudaacacia) is an introduced species to northern Florida, ft is native to the Appalachian and Ozark mountains but has been cultivated in both the eastern and Pacific states as well as in portions of Europe, The black locust can be distinguished from our native locusts by its odd, rather than even, pinnate leaves and by the two sharp spines present al each leaf node.

The ftshfuddle, or tlsh poison tree (Piscidia piscipula). has a long history of practical uses. lis common name derives from its utilization in a primitive system of fish gathering. According to reports of early observers, Jamaican natives were known to strip the fishfuddlc's bark and throw it into shallow pools. The chemicals released from the bark were said to temporarily intoxicate any ftsh in the pool and cause them to turn betiy up arid float to the surface where they could be easily collected. These same narcotic properties also made the ftshfuddle the source of an important anaesthetic, Near the turn of the century the tree's bark and roots were often used to relieve pain during surgical operations.

Piscidia piscipula is also referred to as Jamaica dogwood. This appellation is mis leading in that the tree bears no relation to the Cornaceae. or true dogwood family. The name apparently arose from the tree's use in shipbuilding* Its strong, decay-resistant timber was often used as the central axis, or dog, of ships to insure the vessels" durability and longevity.

Two species of Pithecelhbium are found in southern Florida, The genus name is Greek and alters to both species' twisted, sometimes spiral-shaped pods, T)e more common of the two is probably the black be ad (P, guadaiupense). It grows best on sandy sites and primarily a component of back-dune vegetation along the southeastern coast, l! is found throughout sou the rn Florida and is one of the most common plants in the Keys. Its bright red seeds appear in spring and early summer and are an attractive addition to the plant's duM green foliage.

Another of Florida's native legumes is classified as part of the subfamily Papil-ionoideae. The necklace pod (Sophora tomentosa) is a native of tropical Florida including the southern peninsula and the Keys, and thriven best only in bright sunlight This attractive plant takes its common name from its interesting pods w hich are tightly pinched in between the seeds and take on the appearance of a beaded necklace. Its specific name, umentosa, means densely woolly and refers to the copious covering of silvery hairs that coat the plant's young leaves. This same character has led some to call the plant silver bush. The seeds of the necklace pod are poisonous; ingesting them can cause headache, nausea, vertigo, and respiratory paralysis. Nevertheless, the plant is popular and easily cultivated, and is admired for its long, showy spikes of bright yellow flowers.

The coral bean (Erythrina herhacea) is one of Florida's more showy legumes. Typically a thin-trunked, mult ¡stemmed shrub, it is known to reach heights up to 5 m in the southern part of the state. Its genus name derives from the Greek word "erythros/1 which means red and refers to the plant's brightly colored, tubular ilowers. lis specific name means herbaceous, which is not always accurate for this plant since the trunks of larger individuals are definitely woody. The seeds of the coral bean are poisonous if eaten and are used as rat poison in Mexico. Their colorful flowers are a favorite of the ruby throated hummingbird, and the plant is often planted in suburban hummingbird gardens. The plant typically flowers in the summer and again in the fall and is easy to Find when in bloom.

Shortcuts to Identifying Florida's Leguminous Trees

Florida*s leguminous trees fall into three distinctive categories: those with simple leaves, those with pinnate leaves, and those with bipinnate leaves. Of these groups, those with b*pinnate leaves arc probably the most confusing for the beginning tree enthusiast. This confusion is particularly apparent for specimens that are neither in flower nor in fruit.

Tables 25-1 i P- 97) and 25-2 (p. 98) list the distinguishing characteristics of most of those species that exhibit bipinnate leaves. Fable 25-1 differentiates among the spiny Acacia, all of which have relatively small leaflets; Table 25-2 treats the more easily confused of southern Florida's nonspiny legumes. When used in conjunction with the

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