Abies (Firs)
Morris Arboretum of the University of Pennsylvania 35 taxa, including cultivars

Acer (Maples) - 11 institutions in multi-site collection
Arnold Arboretum of Harvard University 133 taxa, 55 species
Atlanta Botanical Garden 82 taxa
Cornell Plantations 98 taxa
Dawes Arboretum 336 taxa
Hoyt Arboretum 67 taxa
Morris Arboretum 82 taxa
Morton Arboretum 67 taxa
New York Botanical Garden 114 taxa
Quarryhill Botanical Garden 48 taxa
University of British Columbia Botanical Garden 116 taxa
University of Washington Botanic Gardens 209 taxa

Agavaceae (Agave Family)
Desert Botanical Garden 346 taxa

Agave (Agaves)
Arizona-Sonora Desert Museum 65 taxa

Arecaceae (Palm Family)
Arboretum at Arizona State University 300 taxa, 40+ varieties (Phoenix dactylifera, Date Palms)
Fairchild Tropical Botanic Garden 657 taxa
Montgomery Botanical Center 358 taxa

Buxus (Boxwood)
US National Arboretum 137 species and cultivars

Cactaceae (Cactus Family)
Desert Botanical Garden 1319 taxa

Camellia (Camellias)
Huntington Botanical Gardens 40 species, 1200 cultivars
Norfolk Botanical Garden 525 taxa

Carya (Hickories, Pecans)
Arnold Arboretum of Harvard University 18 taxa, 11 species

Cercis (Redbud)
JC Raulston Arboretum 40 taxa

Citrus (Citrus)
Fullerton Arboretum (California State University) 36 accessions, 20 taxa

Clematis (Clematis)
Rogerson Clematis Collection (Friends of) 623 taxa Provisional Status

Cycadopsida (Cycads)
Ganna Walska Lotusland 169 taxa, 3 families, 10 genera
Fairchild Tropical Botanic Garden 150 taxa
Montgomery Botanical Center 222 taxa

Fagus (Beeches)
Arnold Arboretum of Harvard University 26 taxa, 8 species

Geranium (Geraniums)
Chicago Botanic Garden 102 taxa including 85 cultivars

Hamamelis (Witch Hazels)
Green Spring Gardens 80 taxa, 5 species, 75 cultivars

Heaths and Heathers
Mendocino Coast Botanical Gardens - Provisional Status

Hexastylis (Wild Gingers)
Mt. Cuba Center 26 taxa, 68 accessions

Hosta (Hostas)
Toledo Botanical Garden 2500 accessions, 43 species, 357 cultivars

Hydrangaceae (Hydrangea Family)
Norfolk Botanical Garden 190 taxa

Ilex (Hollies)
Scott Arboretum of Swarthmore College 312 taxa
University of Washington Botanic Gardens 47 species

Kalmia (Mountain Laurels)
Highstead Arboretum 78 taxa, 3 species, 69 cultivars, 4 forms, 2 hybrids
Jenkins Arboretum 48 taxa, 65 accessions

Magnolia (Magnolias)
Henry Foundation for Botanical Research 15 taxa (US Natives)
Scott Arboretum of Swarthmore College 138 taxa

Malus (Crabapples)
The Morton Arboretum 185 taxa

Mesoamerican Cloud Forest
San Francisco Botanical Garden 331 species in 182 genera representing 83 families (primarily from tropical mountains of southern Mexico and Central America)

Metasequoia (Dawn-Redwood)
The Dawes Arboretum 9 taxa including 47 wild collected accessions and 8 cultivars

Paeonia (Peonies)
Matthaei Botanical Gardens & Nichols Arboretum 292 taxa (Upjohn herbaceous cultivars) Provisional Status

Quercus (Oaks) - 17 institutions in multi-site collection
Chicago Botanic Garden 48 taxa
Cornell Plantations 77 taxa
Denver Botanic Gardens 61 taxa
Donald E Davis Arboretum 34 taxa Provisional Status
Holden Arboretum 64 taxa
Landis Arboretum 14 taxa
Missouri Botanical Garden 40 taxa
Morris Arboretum of Univ of Pennsylvania 58 taxa
The Morton Arboretum 67 taxa
Mount Auburn Cemetery 25 taxa
New York Botanical Garden 46 taxa
Rancho Santa Ana Botanic Garden 27 taxa
Scott Arboretum of Swarthmore College 52 taxa
Starhill Forest Arboretum 290 taxa
UC-Davis Arboretum 92 taxa
Univ of California Botanical Garden 71 taxa
Univ of Washington Botanic Gardens 86 taxa

Rhododendron (Rhododendrons, Azaleas)
Jenkins Arboretum 1,861 taxa
North Carolina Arboretum 16 species (US native deciduous azaleas)
Rhododendron Species Botanical Garden 300 accessions, 24 taxa including 8 cultivars (Fortunei series)
Tyler Arboretum 529 taxa

Rosa (Roses)
Montreal Botanical Garden/Jardin botanique de Montreal 1097 taxa
Reiman Gardens at Iowa State University 74 taxa (Dr. Griffith Buck cultivars) Provisional Status

Sarracenia (Pitcher Plants)
Atlanta Botanical Garden 78 taxa

Spiraea (Spireas)
Chicago Botanic Garden 52 taxa

Stewartia (Stewartias)
Arnold Arboretum of Harvard University 11 taxa, 7 species
Polly Hill Arboretum 19 taxa

Syringa (Lilacs)
Arnold Arboretum of Harvard University 201 taxa, 22 species

Trillium (Trilliums)
Mt. Cuba Center 71 taxa, 512 accessions

Tsuga (Hemlocks)
Arnold Arboretum of Harvard University 59 taxa, 7 species

Ulmus (Elms)
The Morton Arboretum 73 taxa