In comparison to yesterday’s Zeltnera muehlenbergii, Frasera speciosa is a giant. Individuals can reach heights of 2.5m (8ft), whereas yesterday’s species occasionally reaches 1m, but is often much shorter. There is an age difference, too. Zeltnera muehlenbergii has an annual life-cycle, meaning the individual plants germinate, grow, flower, fruit and die within the span of one year. Frasera speciosa is much different. Once thought to be a biennial (having a two-year life-cycle), David Inouye and Orley R. Taylor Jr. demonstrated that this species is actually a perennial, having a life span that can extend past sixty years (in Oecologia 47(2): 171-174, from January 1980: Variation in Generation Time in Frasera speciosa (Gentianaceae), a Long-lived Perennial Monocarp).
Another intriguing fact one can glean from their paper is that Frasera speciosa is monocarpic, meaning it flowers and fruits in only the last year of its life, spending the remaining decades and years as a mass of leaves. With a range of age before flowering, (minimum age roughly 20 years), how do individual plants ensure cross-pollination? Taylor and Inouye published a subsequent Ecology paper on this topic in 1985, Sychrony and Periodicity of Flowering in Frasera speciosa (Gentianaceae). In short, mature individuals within a population will synchronize flowering in 2-4 year intervals, so that there are peak years (to the extent of >90% of the mature individuals flowering) and low years. What prompts the synchronization is not detailed in these papers, but in some instances, the evidence suggests environmental factors.
One last point: why is it important to know the life-cycle of a plant? In the case of Frasera speciosa, knowledge about its life-cycle can help inform those who use it for economic purposes, e.g., harvesting its roots for medicinal purposes. There is a significant difference in what can be sustainably harvested from a species with a 2 year life-cycle vs. a species with a 20-60 year life-cycle.