Although we have not indicated the geographic 

 origins of the plants, the cultivated woody flora of 

 the southeastern states represents a wide diver- 

 sity of germplasm from many countries, in 

 particular the southeastern United States, 

 Europe, and eastern Asia. In lesser numbers, 

 the catalog lists plants from temperate areas of 

 South America (southern Brazil, Uruguay, Para- 

 guay, northern Argentina, and northern Chile), 

 including Araucaria araucana. Brunfelsia austra- 

 lis, Butia capitata, Calliandra tweediei, Erythrina 

 crista-galli, Sesbania punicea, Tipuana tipu. and 

 others. The diversity of woody landscape plants 

 now in cultivation from South America and 

 Central America suggests that renewed 

 germplasm exploration in these areas would no 

 doubt turn up other plants worth introducing for 

 landscape use in the southeastern United States. 

 Other areas represented in the catalog include 

 Mexico, with Antigonon leptopus. Dioon edule. 

 Parkinsonia aculeata, and some others; South 

 Africa, with Carissa macrocarpa, Ochna 

 atropurpurea, Phygelius capensis, and Tecomaria 

 capensis; and Australia, with Casuarina 

 cunninghamiana, Callistemon (six species), 

 Callitris columellaris. Eucalyptus (six species), 

 and Westringia rosmariniformis. 



Need for the Catalog 



In recent years, the nursery industry has become 

 increasingly active in offering new plant introduc- 

 tions, as a result of renewed interest in plant 

 exploration and germplasm diversity. Each year 

 introductions appear in ever-increasing numbers 

 from all parts of the world. People are now 

 planting a greater diversity of woody landscape 

 plants than ever before in U.S. history. The U.S. 

 National Arboretum has contributed significantly 

 to this flow of new introductions from its plant 

 breeding program and from expeditions to Japan, 

 the People's Republic of China, and the Republic 

 of Korea. Some woody plants totally unknown in 

 cultivation only a few years ago are now best- 

 sellers in garden centers; these include Pyracan- 

 tha 'Mohave' and Hibiscus syriacus 'Diana', both 

 of which resulted from the U.S. National Arbore- 

 tum plant breeding program. 



The influx of new plants has compounded the 

 problems of plant identification and nomencla- 

 ture in the nursery trade, as well as among 

 researchers, students, and home gardeners. 

 Many plants found in the nursery trade are 

 misidentified. The same plant may appear under 

 various names in different nursery catalogs, a 

 problem that leads to nomenclatural confusion. 



We have observed, for example, that dwarf and 

 slow-growing conifers are frequently misnamed 

 in the nursery trade and by the specialists who 

 grow them. Because of this confusion, the need 

 is pressing to investigate the taxonomy and 

 nomenclature not only of landscape plants but 

 also of food, medicinal, and agronomic plants as 

 a much-neglected aspect of horticultural botany. 

 Access to voucher herbarium specimens makes 

 identification of these plants much easier and far 

 more accurate. 



Unfortunately, too few technically qualified 

 botanists or horticulturists are available and 

 willing to tackle the identification and nomencla- 

 ture of landscape plants, leaving many plant 

 groups in a state of perpetual taxonomic and 

 nomenclatural confusion. Although botanical 

 gardens and arboreta often maintain small 

 herbaria to document the plants in their collec- 

 tions, very few of the world's major herbaria are 

 willing to incorporate specimens of cultivated 

 plants for scientific study. The value of voucher 

 herbarium specimens has not been sufficiently 

 appreciated by horticulturists. Many problems 

 related to the taxonomy and nomenclature of the 

 plants in this catalog simply could not have been 

 effectively investigated and resolved without the 

 benefit of herbarium specimens. 



Plant Origins 



The area covered by the catalog encompasses 

 much the same range as J.K. Small's Manual of 

 the Southeastern Flora (1933). This vast region 

 supports the richest ligneous flora in temperate 

 North America and may be compared only with 

 the highly diverse woody flora of the People's 

 Republic of China. More than 250 species of 

 indigenous trees occur in the southeastern 

 United States, many of them grown as landscape 

 plants. One of the best known and admired is 

 Magnolia grandiflora, which ranks among the 

 most valuable indigenous landscape trees of the 

 United States. Now widely cultivated abroad, 

 this magnificent flowering tree is one of America's 

 great gifts to the gardens of the world. 



Because of climatic similarities between eastern 

 Asia and the eastern United States, countries 

 such as Japan, Korea, and the People's Republic 

 of China, with Taiwan, are heavy contributors of 

 woody landscape plants now widely cultivated in 

 the southeastern United States. Some well- 

 known plants of east Asian origin include 



