Permanent Collections
As of December 2025, the permanent collections (which exclude nursery holdings) comprise 16,357 individual plants that belong to 10,519 accessions. These accessions represent 2,160 different species and 1,459 cultivars, which respectively illustrate the Arboretum’s broad biological and horticultural diversity, exceptional for a temperate woody plant collection.
The collections are considered one of the best documented in the world, especially with regard to wild provenance. Many of these lineages are of historical and botanical importance, representing the original North American introductions of eastern Asian plants collected by Arboretum staff such as Charles Sprague Sargent, Ernest H. Wilson, John G. Jack, Joseph Rock, and William Purdom.
Contemporary explorers continue a legacy of plant discovery now guided by the Campaign for the Living Collections.
Read more about the over 150 years’ of plant exploration at the Arnold Arboretum.
Table 1. Taxonomic profile of the Living Collections (Includes Nursery Holdings) of the Arnold Arboretum.a
| RANK | NUMBER |
|---|---|
| Families | 125 |
| Genera | 454 |
| Species | 2,270 |
| Subspecies | 110 |
| Varieties | 314 |
| Formae | 60 |
| Cultivars | 1,476 |
| Interspecific Hybrids | 432 |
| Intergeneric Hybrids | 14 |
Table 2. Provenance of Accessions in the Living Collections (Includes Nursery Holdings) of the Arnold Arboretum.
| PROVENANCE | TOTAL NUMBER | PERCENT OF TOTAL |
|---|---|---|
| Wild | ||
| Direct | 3,299 | 30 |
| Indirecta | 1,023 | 9 |
| Garden | 3,187 | 29 |
| Uncertainb | 3,609 | 32 |
bIncludes 2,514 existing or spontaneous accessions whose provenance cannot be determined.
Dead Collections
Only a minority of the accessions ever attempted to be grown in the collections of the Arnold Arboretum are currently alive—some perished on the grounds, while others representing propagules (e.g., seed, graft, cutting) may have never grown to maturity. The records associated with these legacy collections hold immense value in documenting the history of plant introductions, since the Arboretum facilitated the initial point of entry in North America for many species.
As of December 2025, the legacy collections comprised 109,552 accessions representing 23,686 taxa (kinds). Of these, 71,827 individual plants belonging to 47,584 accessions representing 13,891 taxa (kinds) were inventoried within the living collections (which include nursery holdings) before perishing.
Table 3. Taxonomic profile of the Legacy (Dead) Collections of the Arnold Arboretum.a
| RANK | NUMBER |
|---|---|
| Families | 278 |
| Genera | 1,757 |
| Species | 12,948 |
| Subspecies | 344 |
| Varieties | 1,733 |
| Formae | 320 |
| Cultivars | 9,402 |
| Interspecific Hybrids | 1,721 |
| Intergeneric Hybrids | 107 |
Table 4. Provenance of the Legacy (Dead) Accessions of the Arnold Arboretum.
| PROVENANCE | TOTAL NUMBER | PERCENT OF TOTAL |
|---|---|---|
| Wild | ||
| Direct | 19,873 | 18 |
| Indirecta | 6,297 | 6 |
| Garden | 36,629 | 33 |
| Uncertainb | 46,753 | 43 |
bIncludes 1,736 existing or spontaneous accessions whose provenance cannot be determined.