Is it the one with representatives of the most carnivorous lineages? Going off of the idea that there were 9 independent origins of carnivory — once for the Caryophyllales carnivores, once for Lentibulariaceae, once for Sarraceniaceae, then once for each of the other genera (Brocchinia, Byblis, Catopsis, Cephalotus, Philcoxia, and Roridula), I think Brazil wins — with representatives of 6 of those lineages (2/3 of them!). Assuming this, I believe that’d be followed by Venezuela at 5, Australia and the US at 4, and a whole host of countries with 3. Is that right? If you exclude the bromeliads, I believe Brazil would be tied with Australia at 4, with the US and Venezuela dropping to 3.
What if you’re just counting genera? I think Brazil, the US, and Venezuela are at 7, and Australia (and maybe others) are at 6. I don’t think any single country is higher than 7 genera, but I’m not sure.
But what if you’re counting species? In that case, I think it’s probably Australia, but maybe Indonesia or the Philippines, too. I’d guess that South Africa, Brazil, Venezuela, and Mexico might be up there too. Maybe even the US (how many bladderworts are native to the US?).
What do you think is the best way to measure carnivorous plant diversity? It’s pretty clear that looking at this question from different approaches has different answers. I don’t really know if there’s a right way to look at the question.
Am I missing any other countries with significant carnivorous plant diversity at any of the levels I bring up?