In botany and horticulture, a biennial plant lives for two years, for example Lunaria biennis[?].
... is spread out with 25.2% under the age of 18, 4.8% from 18 to 24, 27.3% from 25 to 44, 28.7% from 45 to 64, and 13.9% who are 65 years of age or older. The median age is ...