A thousand tiny 'sexes' or none?

In the history of botany the late-eighteenth-century discovery and scientific acceptance of 'sexuality' in plants is usually understood as a move from a mere analogy between human and plant to the literal ascription of sex to plants. In subsequent years not only plants but also algae, fungi and bacteria would also be sexed according to the same model. But what does this really entail? This article argues that our tendency to take the large vertebrate mammals (like ourselves) as models when thinking about sex provides a reductive, dimorphic conception of 'the sexes' which may not be appropriate for other forms of life. When sexuality is extended to plants, algae, fungi and bacteria the basic male/female binary of the large vertebrate model is also carried over, but what if, instead, the sex-changing fish or the multiplicity of fungal mating types were our model for 'sex'?