Quercus; multi-site Norfolk Botanical Garden Camellia; 525 taxa Hydrangea; 190 taxa Lagerstroemia; 75 taxa North Carolina Arboretum Rhododendron; 15 spp, native azaleas Phipps Conservatory and Botanical Gardens subfamily Cypripedioideae; 352 taxa Polly Hill Arboretum Stewartia; 19 taxa Powell Gardens Magnolia; multi-site Quarryhill Botanical Garden Acer; multi-site Magnolia (provisional) Rancho Santa Ana Botanic Garden Quercus; multi-site JC Raulston Arboretum Cercis; 40 taxa, including 7 spp, 33 cultivars Magnolia; multi-site Reiman Gardens at Iowa State University Griffith Buck Roses; 75 cultivars Rhododendron Species Foundation and Botanical Garden Rhododendron subsect. Fortunea; 15 taxa, with 104 accessions Rogerson Clematis Garden Clematis ; 709 taxa San Diego Botanic Garden Bamboo; 121 taxa San Diego Zoo Global Cycads; multi-site Orchids; 907 taxa San Francisco Botanical Garden at Strybing Arboretum Arecaceae - high elevation; 107 taxa Magnolia; multi-site Mesoamerican Cloud Forest; 550 taxa, primarily from tropical mountains of southern Mexico and Central America Santa Barbara Botanic Garden Dudleya; 52 taxa Scott Arboretum of Swarthmore College Ilex; 312 taxa Magnolia; multi-site Quercus; multi-site Smithsonian Gardens Orchids - tropical species; 2400 accessions South Carolina Botanical Garden Magnolia; multi-site Starhill Forest Arboretum Quercus; multi-site Taltree Arboretum and Gardens Quercus; multi-site Toledo Botanical Garden Hosta; 495 taxa, including 43 spp, 452 cultivars, with 2500 accessions Tyler Arboretum Rhododendron; 529 taxa, with 1493 accessions United States National Arboretum Buxus; 190 taxa University of Washington Botanic Gardens Acer; multi-site Ilex; 47 taxa Magnolia; multi-site Quercus; multi-site VanDusen Botanical Garden Magnolia (provisional) See also List of botanical gardens and arboretums in the United States National Plant Collection – British plant collections program References External links Botanical gardens in the United States Botanical societies Flora of the United States Plant conservation