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Atlas of United States Trees: Volume 5 - Florida

Introduction

This is the fifth volume of an Atlas with large maps showing the natural distribution or range of the native tree species of the continental United States. In these five volumes, maps of nearly all native tree species of the continental United States have been published. The sixth, a supplement, will contain an index and small maps of the remaining genus of hawthorns (Crataegus). Florida merits a separate volume because it has more native tree species than any other State (except Hawaii), and because it has a large number of tropical species found in no other State. These trees of mostly limited range can be shown better on large-scale map. "Atlas of United States Trees, Volume 1, Conifers and Important Hardwoods" (Little 1971) has an introduction to the series, which may be condensed and adapted here.

Maps demonstrate clearly, graphically, and better than written summaries where the trees grow wild and have many obvious uses. Assembled in atlas form for ready reference, these distribution maps are available to foresters, botanists, and all others interested in trees for use without restriction, since U.S. Government publications are not copyrighted. The native tree species are not distributed across the United States at random, nor are they dispersed equally by States. Some tend to occur, however, in similar patterns related to climate and other factors...

PLANT HARDINESS ZONES

This Florida map is from the Plant Hardiness Zone Map of the contiguous United States prepared by the National Arboretum (USDA Agricultural Research Service 1965). The cold hardiness zones are based on average minimum winter temperatures, that is, the lowest temperature in each year. These zones indicate winter hardiness for certain ornamental plants but are equally useful for native trees. Of course, other factors are involved in adaptation and distribution.

Of the 10 hardiness zones, Florida has the 3 warmest or 5 sub-divisions as shown on this map. From north to south and coldest to warmest, these 5 subzones are listed here, with average minimum winter temperatures in degrees Fahrenheit.

1. Zone 8b, the coldest climate, 15¡ F., in a few counties along the Alabama border in the northwestern part of the panhandle.
2. Zone 9a, 20¡ F., the northern part of the State except near the Atlantic Ocean.
3. Zone 9b, 25¡ F., the central part of the State, except near the coasts.
4. Zone 10a, 30¡ F., the southern part of the Florida mainland north beyond Lake Okeechobee to Cape Canaveral on the east coast to Tampa Bay on the Gulf Coast.
5. Zone 10b, 35¡ F., the Florida Keys and southern end of mainland, north to Indian River County on the east coast and Collier County on west.

Zones 8b and 9a could be grouped with colder zones as having a warm temperate climate. Zones 9b and 10a could be classed as subtropical. Zone 10b could be considered tropical, though with freezing temperatures in infrequent years. However, the Florida Keys are the only areas of the State which never experience freezing temperatures and which are actually tropical...

SUMMARY

"Volume 5. Florida" is the fifth volume of an Atlas showing the natural distribution or range of the native tree species of the continental United States. Florida merits a separate volume because it has more native tree species than any other State (except Hawaii), and because it has a large number of tropical species found in no other State.

The native trees of Florida (excluding hawthorn, Crataegus) mapped in this volume total 262 species...Ten listed species of hawthorn (Crataegus) increase the State total to about 272. The Florida maps have been compiled from various sources...These include publications, herbarium specimens, field work, and review by local specialists. Species maps follow the general plan of earlier volumes. The scale of the Florida base map...is...1:10,000,000. The 98 new maps of tropical hardwoods have the scale roughly 1:4,000,000. Natural geographic distribution of each species is shown as a brown-shaded pattern of fine dots on the black-and-white base map. Outlying stations are plotted by large or small dots. Order of the maps within the 3 lists is alphabetical by scientific name. Scientific and common names follow the Forest Service Check List (1953) except for minor revision on nomenclature. Also, the range of each species, both within Florida and beyond is summarized in text...

Notes on ranges are included. Many tree species of Florida have extensive ranges beyond. Six have broad east-west distribution nearly across the continental United States, while 7 range from Canada to South Florida. Nine temperate tree species of Florida reappear in the mountains of Mexico or also in Central America. Many species are widespread in the eastern half of the continental United States and generally reach their southern limits in northwestern or northern Florida. Most tropical tree species native in southern Florida are present also in the West Indies and southward on the continent. Of the 98 species, 67 are found in Puerto Rico.

Rare and local species are listed. The tropical region of South Florida including the Florida Keys has the greatest collection of rare native trees anywhere in the continental United States, 60 species classed as rare or local. Apparently South Florida has no local or endemic tree species, but 4 endemic tree varieties have been distinguished. However, all these species at the northern edge of their natural ranges would be classed as border or peripheral.

Source:
Excerpt from Elbert L. Little, Jr., "Atlas of United States Trees: Volume 5 - Florida" The United States Department of Agriculture, Forest Service. Washington DC, May 1978, pgs. 1-22.

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