The Arizona State University Vascular Plant Herbarium (ASU) is among the most important in the greater Sonoran Desert region with over 315,000 specimens. We are particularly proud of our holdings of Cactaceae which include over 1,100 chromosome counts. An herbarium is a collection of pressed, dried, and archived plants that are systematically arranged - each specimen a physical record of a plant growing at a particular place and at a particular time. Like most herbaria, we seek to document the geographical and ecological distribution of the regional flora, facilitate research, support teaching, and promote conservation. Vouchers from floristic studies have resulted in comprehensive collections of many important geographic regions in Arizona. ASU Type Specimens: http://swbiodiversity.org/seinet/checklists/checklist.php?cl=2638