The species h.villosa is native to the southeast USA, so it is more heat and humidity tolerant than others. So, Bob was right on suggesting you find plants with h.villosa in their lineage.
I have triple digit temps all summer in my garden, and have only two that don't need a lot of shade ... Obsidian and Paprika. The others I grow, with a lot of neglect, need more shade.
Smiles,
Lyn