Long-term survival and flowering of ocotillo (Fouquieria splendens) in Texas: A 33-year perspective

Abstract

Perennial plants of desert regions can be categorized as short-, moderate-, or long-lived. For long-lived species, the typical range of adult life spans is often poorly known, as well as how reproductive effort is apportioned across years. Ocotillo (Fouquieria splendens), a large shrub of the Chihuahuan and Sonoran Deserts, is considered long-lived and flowers spectacularly, but few data exist on these aspects of its life history. In Big Bend National Park, Texas, I marked 140 mature ocotillos in 1986–1988 at 8 sites and measured inflorescence production. In 1990, 2003, 2018, and 2019, I again measured flower output and determined fates of 95 plants which could be relocated, 64% of which survived the 33-year interval. Smaller plants survived better than larger ones. With an annual survival probability of 0.986, the median plant entering adulthood was projected to live 51 more years. All plants flowered in each study year unless buds froze; means ranged from 8 to 60 inflorescences (approximately 680–5200 flowers) per plant per site. Most survivors made more inflorescences in 2018–19 than 29–33 years earlier. Thus, an average ocotillo produces large crops of flowers for approximately 50 years, an appropriate strategy if seedlings rarely survive.