But what do the wheels represent in this visual metaphor? Are they having sex with their shoes on? What's the sky supposed to be? I'm just not comfortable laughing at ambiguity.
Seed comes almost entirely from the female plant ovule. The male gamete, transported in pollen, makes but a minor contribution in catalyzing the process. Hell, many plants form fruit and sometimes even unfertilized yet viable parthenogenetic seeds without male genetic contribution. Seed is a poor metaphor in this instance.