Plant reproductive morphology is the study of the physical form and structure (the morphology) of those parts of plants directly or indirectly concerned with sexual reproduction.

Among all living organisms, flowers, which are the reproductive structures of flowering plants (angiosperms), are the most varied physically and show a correspondingly great diversity in methods of reproduction. Plants that are not flowering plants (green algae, mosses, liverworts, hornworts, ferns and gymnosperms such as conifers) also have complex interplays between morphological adaptation and environmental factors in their sexual reproduction.

The breeding system, or how the sperm from one plant fertilizes the ovum of another, depends on the reproductive morphology, and is the single most important determinant of the genetic structure of nonclonal plant populations.

Christian Konrad Sprengel (1793) studied the reproduction of flowering plants and for the first time it was understood that the pollination process involved both biotic and abiotic interactions. Charles Darwin's theories of natural selection utilized this work to build his theory of evolution, which includes analysis of the coevolution of flowers and their insect pollinators.

Plants have complex lifecycles involving an alternation of generations. One generation, the sporophyte, produces spores which then grow to become the next generation, the gametophyte. These produce gametes, the eggs and sperm, which then unite and grow to become sporophytes, completing the cycle.

Spores may be identical (isospores) or come in different sizes (microspores and megaspores), but strictly speaking, spores and sporophytes are neither male nor female because they do not produce gametes. The alternate generation, gametophytes, can be monoicous (bisexual), where an individual can produce both eggs and sperm, or dioicous (unisexual), where one produces only eggs and another produces only sperm.

In the bryophytes (liverworts, mosses, and hornworts), the sexual gametophyte is the dominant generation. In ferns and seed plants (including cycads, conifers, flowering plants, etc.) the sporophyte is the dominant generation; the obvious visible plant, whether a small herb or a large tree, and the gametophyte is very small. In bryophytes and ferns, the gametophytes are independent, free-living plants, while in seed plants, each female megagametophyte, and the megaspore that gives rise to it, is hidden within the sporophyte and is entirely dependent on it for nutrition. Each male gametophyte typically consists of two to four cells enclosed within the protective wall of a pollen grain.

The sporophyte of flowering plants is often described using sexual terms (e.g. "female" or "male") based on the sexuality of the gametophyte it produces. For example, a sporophyte that give rise only to male gametophytes may be described as "male", even though the sporophyte itself is asexual, producing only spores. Similarly, flowers produced by the sporophyte may be described as "unisexual" or "bisexual", meaning that they give rise to either one sex of gametophyte or gametophytes of both sexes.^{[page needed]}