INTRODUCTION TO THE CATALOG 



On the following pages is a list of the families, genera, and species 

 of Southeastern aquatic plants. These follow the order of Robinson 

 and Fernald's seventh edition of Gray's New Manual of Botany, If 

 more than one species of a genus is present in the region, a key to the 

 species follows the generic name. In the case of the Gramineae, the 

 Cyperaceae, and the Alismaceae, illustrated keys within the family 

 are included, as these groups are in most cases not carried to the genus 

 in the main key. 



The species list is annotated as to the range and habitat of the plants. 

 Range is given not only as to political units but also is stated in terms 

 of the physiographic regions involved. These physiographic regions 

 are delimited on the frontispiece map and a few remarks on them 

 follow. For economy of space statements of range, habitat, and fre- 

 quency are usually given in phrases rather than complete sentences. 



The Coastal Plain, which is a region made up of recent sediments 

 lying adjacent to and extending back from our coasts, is the most 

 important from a malariological point of view. The length of this 

 guide is due in part to its rich aquatic flora, which is often quite 

 different from that of the more northern regions such as are so well 

 treated by Fassett in A Manual of Aquatic Plants. The subdivided 

 Mississippi Valley is geologically similar to the Coastal Plain but is 

 here differentiated because it has a distinctive flora. 



The Piedmont, which consists of crystalline rocks or soils derived 

 therefrom, has few extensive aquatic areas and is thus of less im- 

 portance from the point of view of mosquito breeding. The Blue 

 Ridge is also of little interest, and aquatic plants found in our terri- 

 tory only in the mountams are not considered in this guide. The 

 paleozoic Appalachian Provinces and the Interior Low Plateaus do 

 have a problem, along their larger rivers, especially in the vicinity of 

 impoundments. 



Also annotated are synonyms when nomenclature in this treatment 

 differs from that offered by Small, Manual of the Southeastern Flora. 

 A few notes on the association of mosquitoes with specific plants are 

 given, but sufficient knowledge is lacking to make extensive general- 

 izations. 



A recently introduced species, the water-chestnut (Trapa natans L.), 

 has not been recorded from our territory but occurs nearby in the 

 Potomac River, where it has been found harboring Anopheles quad- 

 rimaculatus. It is not listed in this catalog. 

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