biennis

Biennis is a Latin adjective meaning “biennial” and is used in botanical naming to indicate a two-year life cycle. In plant biology, biennials are species that require two growing seasons to complete their life: vegetative growth in the first year, followed by flowering and seed production in the second, after which the plant typically dies. Many biennials form a rosette of leaves in their first year, storing energy to fuel a flowering stalk in year two. Flowering is often triggered by cold exposure (vernalization) and other environmental cues such as day length and temperature; the timing of bolting varies with climate and species. Seed production completes the cycle, and in many species the seed can persist in the soil as a short-term seed bank.

Gardeners encounter biennials both as ornamental and edible crops. Classic garden biennials include foxglove (Digitalis), hollyhocks (Alcea), and sweet William (Dianthus barbatus). Some crops grown for two-year production, such as carrot (Daucus carota) and parsnip, are treated as biennials in their cultivated form, though many are harvested after a single growing season. Because climate can alter life strategy, some taxa behave as biennials in temperate regions but act as short-lived perennials in milder climates.

Cultivation notes: to establish biennials with a two-year bloom cycle, gardeners may sow them so that the first year provides a vigorous rosette, then allow flowering only in the second year. Seeds often benefit from cold stratification. The term biennis appears in species names to reflect this two-year development pattern.

Etymology: biennis derives from Latin bi- “two” and annus “year.”