A developmental classification system for the comparison of Puya raimondii giant Andean rosettes

Abstract Puya raimondii Harms, an endangered giant bromeliad, has great ecological and cultural significance in the Central Andes. To help studies of population size structure in this species, this study aims to develop a rapid classification system based on plant developmental stages instead of using absolute size measurements, and applies it to three areas in or near Huascarán National Park, Peru. Plant height, stem height, total and photosynthetically-active rosette diameter and height to the base of the rosette were measured, to illustrate how the developmental stages compare, along with estimates of vegetation, rocks, and bare ground. Five plant developmental stages were identified in the study: juvenile, subadult, adult, reproductive adult, and senescent reproductive adult. The juvenile stage could, in future, be further divided into smaller, vulnerable plants and more established juveniles, but this requires more detailed study to determine appropriate distinguishing developmental criteria. Comparing locations, Puya plants in Queshque, were smaller than in the other locations, across all developmental stages. However, the environmental variables recorded in this study could not explain this difference, indicating the importance of other, unknown factors. This study provides an efficient and informative classification system for P. raimondii giant rosettes, using well-defined developmental stages, that can reveal important differences between populations and prompt the generation of new hypotheses about the ecology of these important plants. The classification system could be applied in populations across the species’ distributional range in the Central Andes to explore how age, size and environmental factors affect growth and development in this species.