Okay, I may have stumbled onto the basis for Holzer's chart. Here's a plant taxonomy chart that shows the classifications. This isn't Holzer's. His is bigger and a lot more elaborate. But this one is listing all the plants that he keeps talking about as the foundational plants to include in a food forest. this chart is relating to wheat gluten and how it branches off separately from the other grains, if that's a help to anyone.