Biennial plant

Biennial plants (also called bienne or winter annual plants) are herbaceous plants whose life cycle (from germination to seed formation) lasts two years , more precisely two vegetation seasons, i.e. not two years in the calendar sense, but one vegetation period before the climatically unfavorable time (frost / Winter or dry season ) and one after that . Biennial plants differ on the one hand from annual , summer annual plants, which only live for one growing season, and on the other hand from "real" perennials , which live for more than two growing seasons.

In the first year after germination , biennials remain purely vegetative, i. In other words, they only develop roots and foliage in order to store nutrients - the flowers and fruits with seeds, on the other hand, only develop in the second vegetation period (after the frost or the dry season). Under favorable climatic conditions and if sown early, some biennial plants can develop flowers in the first year . After the seeds ripen, however, the two-year-olds, like the one-year-olds, always die. Well-known examples of two-year-olds are - contrary to its name actually two-year-olds - annual silver leaf or the giant hogweed ( Heracleum mantegazzianum ).

Crops

Some biennial crops that do not primarily use fruits or seeds are only grown as annuals. A well-known example is the beet . Their roots can only be used in the first year. In the second year, the stored nutrients would be used up for flower formation.

Some examples of biennial crops: