Navaea phoenicea (Malvaceae) is a flagship shrub species endemic to Tenerife Island in the Canary archipelago and is included as Endangered on the Spanish Red List. We conducted a comprehensive census and monitored the structure of eight accessible populations over 10 years to develop a stage-based demographic matrix model and performed deterministic and stochastic projections. To determine the longevity of individuals, we conducted a dendrochronological study on ten collected dry samples. The censuses showed a clear, gradual decline, and the total population was around half that in previous studies. The yearly finite growth rate was strongly correlated with annual rainfall. Survival rates of seedlings were low, and high elasticity values were allocated to the larger, reproductive individuals, which showed the highest survival rates. The age of the oldest individual was 32 years, while the average age inferred from dendrochronology was 18 years. These results point to a lower longevity of individuals with respect to the values calculated by demographic models. The findings of this study suggest the importance of the preservation of reproductive individuals and their habitat, as well as the need to re-adopt legal measures of greater protection for the species.