Must the state prove by way of lab results that the alleged substance is in fact a controlled substance?

PC 1.07(12) defines "controlled substance" as in H&SC 481.002, so absent a specific statute or case to the contrary, I would think the jurisprudence from the Controlled Substances Act would govern that part of the PC as well.

Our experience in the Special Prosecution Unit (where this is our most common charge) is that anything that can’t be proven by training and experience (like marijuana pre-hemp laws) requires lab tests and expert testimony to prove what the substance actually is, and then testimony that the substance is actually on the CS list.