Assessing the Status of a Pre-Contact Agave Cultigen, Agave Murpheyi

Abstract

Nearly four decades of cross-disciplinary research have resulted in the documentation of six agave cultigens that were cultivated in pre-contact Arizona. Among these is Agave murpheyi F. Gibson, known to have been farmed by the Hohokam in the Sonoran Desert. Though cultivation of this species declined around ca. 1450 CE, plants of A. murpheyi have persisted presumably in the previously agricultural sites, by means of their asexual reproduction and many adaptations to the arid climate. Despite the apparent resilience of this species, A. murpheyi is now rare and at risk of extinction. The situation may be worsened by increased regional drought and disturbances to habitat such as development, livestock activity, and recreation. Since A. murpheyi is not eligible for federal listings in the U.S. that protect threatened and endangered species, human intervention may be necessary to support the survival of this biocultural resource. This study presents the first census of A. murpheyi involving complete ramet counts and analysis of height class structures. Height class proportions and mean ramet height within clusters (groups of ramets) were compared across 15 sites in Arizona between Feb. 2022 and May 2023. Multiple habitat characteristics and their effects on ramet height were also evaluated: 1) presence/absence of nurse plants and packrat middens, 2) levels of site disturbance, and 3) proximity to archaeological features. Mean ramet height within clusters (MRHC) was significantly different across the 15 sites, however, no significant differences were found between height class proportions and MRHC with any habitat characteristics as factors. Documentation of ramet numbers and height class structures at these sites provides an indication of population status and baseline data to evaluate future trends in population size. This study also provides a protocol for continued monitoring of A. murpheyi, an important foundation for continued work to protect this species.