About Pentachaeta lyonii A.Gray
Pentachaeta lyonii A.Gray generally grows in compact soil with little disturbance and very few competing plants. While this species has been successfully cultivated in greenhouses using light, well-aerated soil, it remains unclear whether it naturally grows in compact soil due to lack of competition or because of specific nutrient requirements. This plant relies on insect pollination to produce seeds. Historically, 43 populations of Pentachaeta lyonii were found across the Santa Monica Mountains, Simi Valley, Palos Verdes Peninsula, and Catalina Island. A 2006 survey only located 21 remaining populations, and populations on the Palos Verdes Peninsula were already considered extirpated by that time. Populations on Catalina Island were also thought to be extirpated until 112 individual plants were rediscovered there in 2011, growing on a ridgeline near Two Harbors. Stunt Ranch was the most recent area where the species was suspected to be extirpated: no flowering individuals have been observed there since 1990, following an 8-year population decline. In 2020, botanists with the Catalina Island Conservancy spotted this rare species again on Catalina Island. Only 19 individuals were found at a site that roughly matches the location of a historical record made by W.S. Lyon, the botanist who first discovered the species in 1885. Pentachaeta lyonii was granted protected status in 1990.
