Flowering

Flowering is the reproductive phase of angiosperms, during which a plant forms flowers that enable fertilization and seed production. The transition from vegetative growth to flowering is controlled by a combination of environmental cues, such as day length (photoperiod), temperature, and resource status, and by internal genetic programs. Photoperiodic timing distinguishes long-day and short-day species; many plants also require a period of cold (vernalization) to initiate flowering. Some species are day-neutral and flower independently of day length.

Molecularly, flowering involves integration of signals at the shoot apical meristem. In model plants, mobile signals such as FLOWERING LOCUS T (FT) act as florigen and move from leaves to the meristem to trigger floral development; repressors like FLOWERING LOCUS C (FLC) can delay flowering and are reset by vernalization. Hormones, notably gibberellins, also influence flowering in some species, particularly under non-inductive photoperiods.

Development proceeds from an indeterminate vegetative meristem to an inflorescence meristem and then to floral organ primordia, typically forming four whorls: sepals, petals, stamens, and carpels, though floral architecture varies. After pollination and fertilization, ovules develop into seeds, and the surrounding ovary becomes fruit. Some species rely on animal pollinators or wind; a few reproduce asexually or without fertilization (apomixis).

Flowering has major ecological and agricultural importance. It influences plant lifecycles, ecosystem interactions, and crop yields, and is a focus of horticulture and breeding, which aims to control flowering time, flower form, and vase life.