Many plants reproduce by a mixture of outcrossing and self-fertilization.
To a population geneticist that means that they reproduce by a mixture of selfing and random mating. Now I'm going to pull a fast one and derive the equations that determine how allele frequencies change from one generation to the next without using a mating table. To do so, I'm going to imagine that our population consists of a mixture of two populations. In one part of the population all of the reproduction occurs through self-fertilization and in the other part all of the reproduction occurs through random mating. If you think about it for a while, you'll realize that this is equivalnt to imagining that each plant reproduces some fraction of the time through self-fertilization and some fraction of the time through random mating.