Definition: Of life span, a plant which lives for more than one but less than two years after germination, c.f. annual, ephemeral, perennial, of flowering with respect to architecture, hapaxanthic, monocarpic, pleonanthic.
Definition: Of seed bank longevity. Seeds germinate in the first favourable season after dispersal. Generally, seed bank longevity is <= 1 yr (no persistent seed bank).