Asian Germplasm in American Horticulture: New Thoughts on an Old Theme

North American ornamental horticulture includes in its cultivated flora, examples from nearly every floristic region of the globe, yet by virtue of a predominantly temperate climate relies heavily on plants derived from the Holarctic kingdom, the dominant floristic kingdom of the northern hemisphere. The historically East Coast-centric horticulture community in the United States gardens is the North American Atlantic floristic region, an area that covers most of the continental U.S. from the Atlantic to Gulf States and through the Great Plains.   This floristic region is linked through a common evolutionary path to the Eastern Asiatic floristic region, which encompasses parts of Far East Russia, the Korean peninsula, Japan, Taiwan, and mainland China to the eastern Himalayas.  The success of Asian germplasm in American horticulture is due in part, to this shared evolutionary history, climate matching, and pre-adaptability. The East Asiatic floristic region is one of the most diverse in the world, with a high level of endemism across taxonomic ranks and ancient relicts of a once widespread flora. From this, a large number of ornamental genera and species have been introduced, from either a long history of cultivation in Asia or directly from the wild, where they have since become fixtures in European and American gardens. With regard to woody ornamentals, about 700 have been identified for potential inclusion in the U.S. Department of Agriculture (USDA) National Plant Germplasm System (NPGS), more than 50% of these include species from Chinese, Japanese, or Korean floras. Access to these genetic resources is now governed by international treaties, particularly the Convention on Biological Diversity (CBD) and the Nagoya Protocol. Plant genetic resources within the NPGS system are open access, which requires significant vetting of newly acquired germplasm from countries that are party to the CBD.  Furthermore, updated plant quarantine regulations have added an additional hurdle to the importation of foreign plant genetic resources.  The newly created category within USDA Animal and Plant Health Inspection Service (APHIS) Q37 regulations, not authorized pending pest risk analysis (NAPPRA), restricts the import of plants that may harbor pests or become pests that affect American agriculture. To this end, scientists involved in the collection or utilization of Asian plant genetic resources are affected by recent changes in international and national laws.