[2] In addition to a library and a historical collection (archive), the institution also has an extensive herbarium of over 800,000 specimens documenting wild and cultivated plant diversity.

[1] The act authorized the creation of the arboretum on what was then called Mount Hamilton, but it did not actually appropriate any funding to make that happen.

[8] Additional land was purchased in 1938, 1948, and 1949 that, along with subsequent minor expansions, contributed to the Arboretum's current footprint of 446 acres (180 ha).

A groundbreaking was held in 2016 but the garden was reportedly cancelled due to counter-intelligence concerns regarding the construction of a large pagoda that could be used for collecting signals intelligence.

The arbor leads to a large plaza with a flagstone star and a wall adorned with pottery tiles designed and fabricated by Liza Bach, a Tennessee crafter.

The collections of the National Bonsai and Penjing Museum are found throughout the Japanese, Chinese, and North American Pavilions, as well as a conservatory.

[11] The Mary E. Mrose Exhibit Gallery features season and rotating displays of bonsai as well as a collection of viewing stones.

Among the many bonsai accessions is a Japanese white pine cultivar, Pinus parviflora 'Miyajima', donated in 1975 by Masaru Yamaki to mark the United States' bicentenary.

[15] Featuring three panels of classical Japanese inscriptions, the bell stands 27 inches tall and weighs 80 pounds.

A small collection of public artwork, including Split Ritual by American sculptor Beverly Pepper, can be found at the Arboretum.