This stress can also actually change the physiology (internal function) of plants in some cases. One study made use of deer exclosures to examine the proliferation of invasive Japanese stiltgrass. In places without fences and plentiful deer, unsurprisingly, there was a strong negative effect on the amount native plant species. More interesting, summer deer feeding led to smaller leaves on many plants, including some invasives. The Japanese stiltgrass and garlic mustard actually upped their photosynthesis process, and natives like Trillium showed a drop in their maximum photosynthetic rates.