Invariables and variables in the evolution of plant reproduction

Abstract

AbstractLand plants have undergone great diversification and evolution in the past 400 million years. Although complex and hard to grasp, the sexual reproductive cycle (SRC) is an important unavoidable process in the evolution of plants. Various modifications have been added sequentially to this core process, thus creating various novel organs and distinguishing their bearers from one another. Reproductive organs of all land plants, including sporangium, megasporangium, metamegasporangium (=ovule), and various metamegasporangium complexes, are derived from terminal sporangia in the earliest land plants. Throughout the million‐year‐long evolution, plants sequentially recruit associating accessories to protect their vulnerable core parts (spore and gamete). The occurrence of every single one of these novelties is a stair marking land plant reproduction evolution and leads to enhanced offspring development conditioning.