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New Living Collections Plan for the Cactus and Agave Families


by Dr. Joe McAuliffe, Director of Research, Conservation and Collections

The Desert Botanical Garden has one of the world’s most impressive living collections of the cactus and agave families (Cactaceae and Agavaceae). The breadth, prominence, and importance of those collections received national and international acclaim in 2010 when the North American Plant Collections Consortium (NAPCC), a group within the American Public Gardens Association (APGA), designated our Cactaceae and Agavaceae collections as the National Collections for these two families [see The Sonoran Quarterly Vol. 64(4), 2010, p. 4-7 for article by R. Puente].

In order to properly plan for the growth and care of the living collection, a team of Garden staff developed a far-reaching, comprehensive collection plan for both families. In July 2012 the Board of Trustees unanimously approved and adopted this new plan as a blueprint for further enlarging and improving the collection over the course of the next quarter century.

Parameters and Management Issues

A collection plan for any museum is more than simply a list of items (in our case, living plants) that the institution wishes to acquire. A thorough plan also includes detailed consideration of how the collections contribute to an institution’s mission as well as how those collections will serve various groups. Acquiring, housing, and caring for any collection require resources such as facilities, personnel, supplies, and funding. A collection plan that is in accord with mission-related, institutional priorities helps ensure the wise use of limited financial resources and also helps the process of procuring additional financial support.

To create the new collections plan, 14 staff members of the Research, Conservation and Horticulture Departments worked together for nearly two years to assess the current collection, determine needs and priorities for the future, and devise solutions for significant collections management challenges. With input from the Research and Horticulture Committee, one of the standing committees of the Board of Trustees, five groups of stakeholders that use the collections were identified. The five groups are (1) visitors, tourists, and horticulture hobbyists, (2) K-12 teachers and students, (3) conservation partners, (4) researchers and the higher education community, and (5) commercial horticulture partners. Input from representatives of these groups contributed to a plan that better serves many different needs.

Before considering details of how to enlarge the collection, the Collections Planning Working Group first grappled with issues related to effective management and care of the existing living collection. One of the issues involved development of a process by which seeds are acquired and used. This was needed because the Garden’s seed collection had grown substantially but there was little coordination between acquisition efforts and specific plans for using the seed. A new process was created that facilitates the acquisition of seed resources that fit within the collection plan and also tracks these acquisitions to ensure that they are used as originally planned.

The second management challenge involved losses of species from the existing collection. Botanical gardens typically care for many thousands of different species, with the consequence that some species are represented by very few (sometimes only one or two) genetically distinct individual plants. Species represented by so few individuals are at great risk of loss from the collection, necessitating reacquisition from other sources if that species is desired as part of the collection. It was recognized that new information management tools and management processes were necessary in order to prevent these kinds of losses. Accordingly, the Desert Botanical Garden Red List process was created in which staff task groups regularly review updated collections records and identify species whose numbers have fallen to one or two individuals. The task groups then plan and prioritize management actions, such as propagation or acquisition of additional plants.

The name Red List was borrowed from the International Union for the Conservation of Nature (IUCN) Red Lists of endangered species.The IUCN Red Lists likewise provide tools that allow conservationists to recognize threatened species and devise strategies to prevent species extinctions.

Planning the Growth of the Living Collection

Once the group had created and implemented these two management approaches, work on planning how to increase the breadth of the current collections began in earnest. To do this, two new information databases were created that contain information on all known species of the two families, a variety of information about each species including geographical occurrence, environmental conditions, and conservation status, and whether or not the Garden currently has growing representatives or seeds of each species. These databases enabled a detailed assessment of current gaps within the Garden’s collections, the assessment of horticultural requirements of different species, and planning for incremental increases in the collection over time.

For example, the gap analysis for the cactus family indicated that the Garden currently possesses about half of the approximately 2,000 species of cacti found in the Western Hemisphere, (see Figure 1), including about three-quarters of the species from the southwestern United States and the Baja California peninsula, Mexico. About half of the species from mainland Mexico are represented and about a third of all species from arid and semi-arid regions in southern South America (Peru, Chile, and Argentina) are in our collections. A far smaller fraction of species from the humid tropics of Central America and tropical South America are held by the Garden, and this is understandable, as those species require environmental conditions that are difficult, at best, to provide in current Garden facilities.

The Collection Plan states that “The Garden’s cactus and agave family collections will focus on species from warm temperate, subtropical, and tropical arid and semi-arid regions of the world. The Garden will acquire and maintain only those living plant species for which it has the facilities that provide the environmental conditions necessary for maintaining plant health and vitality. This is the first, foundational step to ensure the survival and perpetuation of plant species under our stewardship and care in the living collection.”

Even though the focus of our current and future collections is on plants from the world’s drylands, the Living Collection Plan nevertheless outlines a means by which the Garden will initiate the process of creating multi-institutional NAPCC National Collections for the cactus and agave families. By including other institutions from other climate regions in the U.S., the National Collections of the two families can be expanded to include species that are unsuited for the hot desert climate of Phoenix, such as those from the humid tropics. In this vision, a collection consisting of all species from both families can be created, with the Desert Botanical Garden taking the lead in creating and maintaining an integrated database.

Key Goals for the Future

The Living Collection Plan for the cactus and agave families outlines short-, medium-, and long-term goals to be accomplished over the next 25 years.

Here are some of the main goals for each period:

Short-term goals (through 2016):

Medium-term goals (2017-2021):

Long-term goals (2022-2036):

The last item listed above is envisioned as a unique exhibit of giant succulent plants from seasonally dry, tropical regions of the world. This exhibit could include the most massive cactus that exists, Pachycereus weberi, which is found in semi-arid climates of tropical Mexico. Together with giant succulents like this from the New World, other plants that would be included are the wondrous and magnificent giant water-storing plants of the Old World, including giant candelabra and tree euphorbias of southern Africa, baobabs and bottle trees of Africa, Madagascar, and Australia, and the bizarre dragon trees of the island of Socotra, off the horn of Africa. This exhibit would display these magnificent and unusual plants in a way that is not currently done at any botanical garden in the world. Creation of this exhibit in a dramatic conservatory structure by 2036 would be a spectacular way to usher in the Garden’s centennial in 2039.

The new Living Collections Plan represents the first time the Garden has developed such a thorough and detailed analysis of existing collections along with a vision for future collections. Over the next several years, similar efforts will be made to develop collections plans for other plant groups, including Old World succulents and trees and shrubs. In addition, the Garden’s herbarium and library also represent important institutional collections, so detailed collection plans will be created for them.

Taken together, the considerable amount of thought and work that will go into all of these collection plans will make our institution a leader among botanical gardens and our desert collections among the most important and impressive in the world.

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