Plietesials

Plietesials are perennialflowering plants that grow for many years without flowering, then flower gregariously (synchronously), set seed, and die. The length of this cycle usually varies between 8 and 16 years. For example, the neelakurinji plant (Strobilanthes kunthiana), in the family Acanthaceae, flowers predictably every 12 years, blooming as expected in 2006 and 2018 in the Munnar region of Kerala, India.

Other commonly used expressions or terms describing a plietesial life history include gregarious flowering, mast seeding, and supra-annual synchronized semelparity (in botany, semelparity is more specifically referred to as monocarpy).

Certain species in unrelated families of flowering plants, such as in the Arecaceae, Scrophulariaceae, Fabaceae, Apocynaceae, and Acanthaceae, are plietesial. This type of life history is especially well-known among certain species of bamboo (family Poaceae), some of which have a flowering cycle of 40 to 50 years. It remains unclear why gregarious flowering after long intervals of vegetative reproduction is so invariably associated with death shortly after flowering, although both are associated with higher reproductive outputs.