Number of insect species per plant species for various regions (i.e. the Cape Floristic Region, temperate zones, tropical zones).

The number of insect species per plant species is significantly higher in the tropics than the CFR, although this is entirely confounded by plant growth form. The CFR does not have significantly more insect species per plant species than other temperate zones, suggesting regional plant richness and growth form are better predictors of regional insect richness than environmental variables.