Yes...or tomatoes, for that matter. That's my understanding of the importance of the Harrison Act vis-a-vis drug (controlled substance) enforcement. Because we are blessed with the God-given rights to life, liberty and pursuit of happiness, and assuming that consumption of tomatoes is one person's chosen path toward happiness, it would be entirely UNLAWFUL and UN-Constitutional for Congress to pass a law prohibiting the CONSUMPTION of tomatoes.
BUT, by passing a prohibitive tax measure on tomato production, transportation or possession, the Harrison Act TRANSFORMS the 'hidden' objective of Congress (preventing the people from consuming tomatoes) into a perfectly Constitutional activity.
Without the Harrison Act and the Supreme Court's interpretation of it (that you cited), Citizen's throughout our Country would be free to imbibe in marijuana consumption, opium consuption, cocaine consumption, methampetamine consumption, and on and on, in pusuit of their individual strivings toward 'happiness' at will!
I believe this reasoning was reversed in 1969, when the Marihuana Tax Act was declared unconstituional.