The University of Arizona Herbarium (ARIZ) houses a research collection of over 420,000 preserved plant specimens, including nearly 1500 type specimens. ARIZ is the largest herbarium in Arizona; we estimate that about one third of our collection is from Arizona and one third from Mexico.
All of our specimens from Arizona (and more than half of our specimens overall) have been entered in our database. Contact us for information about our holdings beyond Arizona, which may or may not be in the database yet.
Access to the physical collections is available for researchers and the general public, after having been trained in standard herbarium protocol. Loans can be arranged for researchers not local to Tucson, and the increasing number of specimen images available online provide an instantly available alternative.
The collections are arranged by family number according to the most recent evolutionary understanding (see separate lists of families and family numbers). The flowering plants are arranged according to the Angiosperm Phylogeny Group III classification system. Within families, genera and species are organized alphabetically. Within species, specimens are grouped by region in colored folders, as indicated below.
Within species, specimens are grouped in color-coded folders by region, as follows:
Yellow - Arizona
Pink - United States (excluding Arizona), Canada & Greenland
Green - Mexico and the remainder of the Americas, including Caribbean Islands
Brown - Old World
White - Cultivate specimens, regardless of region
Exceptions are noted prominently at the appropriate locations in the herbarium.
In addition to the regular collection, types are stored separately, as is the boxed collection of large fruits and cones. There is also a collection of seeds, and small holdings of bryophytes and lichens.