Frasera speciosa (Gentianaceae) is a long-lived monocarpic herbaceous perennial found commonly in the Colorado Rocky Mountains. It grows for many years (possibly up to 100 years in alpine populations) as a basal rosette before producing a large inflorescence (as tall as 3m at lower altitudes) in its final year. It is mast flowering, with 2 – 7 years between flowering events, which I have tracked since 1978. Plants preform both leaves and inflorescences, with approximately four times as many pre-formed leaves as current leaves, which suggests that inflorescences are also pre-formed. In a search for an environmental cue that might synchronize flowering, I included lag times of up to four years, and found a strong correlation (r2 = 0.660. p<.0008) between May – July precipitation and number of plants flowering four years later (n = 12 years with >1,000 inflorescences, range up to 31,117). Herbivory by a specialist Pallopterid fly could be one factor selecting for the periodic mast flowering, and opportunities for cross-pollination may too (although plants can self-pollinate through geitonogamy). The insights gained by this study are only possible with a commitment to a decades-long research program, which is facilitated by work at a field station (Rocky Mountain Biological Laboratory).