The remaining genitalia were then reconstructed to resemble those of the chosen sex.
Thus our Japanese knotweed is incapable of setting seed, although it does occasionally do so by crossing with other (alien) species of knotweed.
Some of our most familiar wild plants, such as nettle and red campion, are dioecious.
An interesting situation arises when only one sex of an alien dioecious plant is imported into the UK.
This means that apart from bits of rhizome being washed down rivers, it can only get around by being moved around in contaminated soil.
The frequency with which it does this is a sign of just what a careless bunch we are.