Collection Statistics

Permanent Collections

As of May 2025, the permanent collections (which exclude nursery holdings) comprise 16,270 individual plants that belong to 10,487 accessions. These accessions represent 2,149 different species and 1,451 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.

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Table 1. Taxonomic profile of the Living Collections (Includes Nursery Holdings) of the Arnold Arboretum.^a

RANK	NUMBER
Families	123
Genera	443
Species	2,249
Subspecies	112
Varieties	317
Formae	60
Cultivars	1,465
Interspecific Hybrids	435
Intergeneric Hybrids	14

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Table 2. Provenance of Accessions in the Living Collections (Includes Nursery Holdings) of the Arnold Arboretum.

PROVENANCE	TOTAL NUMBER	PERCENT OF TOTAL
Wild
Direct	3,290	30
Indirecta	995	9
Garden	3,086	28
Uncertainb	3,618	33

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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 May 2025, the legacy collections comprised 108,152 accessions representing 23,501 taxa (kinds). Of these, 72,535 individual plants belonging to 48,202 accessions representing 13,772 taxa (kinds) were inventoried within the living collections (which include nursery holdings) before perishing.

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Table 3. Taxonomic profile of the Legacy (Dead) Collections of the Arnold Arboretum.^a

RANK	NUMBER
Families	275
Genera	1,735
Species	12,859
Subspecies	342
Varieties	1,729
Formae	318
Cultivars	9,313
Interspecific Hybrids	1,719
Intergeneric Hybrids	107

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Table 4. Provenance of the Legacy (Dead) Accessions of the Arnold Arboretum.

PROVENANCE	TOTAL NUMBER	PERCENT OF TOTAL
Wild
Direct	19,645	18
Indirecta	6,067	6
Garden	35,557	33
Uncertainb	46,883	43