1.
in sexual reproduction, the union of two types of sex cells that are dissimilar in size, structure, and function
2.
the alternation of sexual and asexual reproduction in some species such as aphids in which every other generation is produced from the female with no need for a male
3.
the production on the same plant of two kinds of flower, one bearing both male and female organs and the other bearing only female organs or being asexual