Aspects of seasonality.

The seasons are astronomical, astrological, meteorological, biological, and agricultural. From a perspective outside the biological sciences, the questions of interest about plant seasonality are linked to this wider context. In this review I try to see flowering time, as one important aspect of seasonality, from an outsider's point of view, and describe what is known about it in different types of plants. What is known about it is conditioned by what particular scientists have asked about it, so the variety of approaches to seasonality is another point of emphasis. Detailed consideration is given to flowering seasonality in perennials compared with annuals, and both molecular and whole plant perspectives are presented.