That's been my experience with it. For me, the literalness of "plant spirit" is accepted reality. In the circles I hang out with, we don't put the term, plant spirit, in air quotes.

Generally, the two plants that are combined are the Ayahuasca vine, which contains the various MAOI, and Chacruna, which contains DMT. Many plants yield DMT, though only some plants yield a sufficient concentration to be useable.

From an experiential point of view, the plant material of Ayahuasca and Chacruna are the material body. They each have a specific intelligence that is sentient, and conscious, and responsive to the ikaros (the song sung in ceremony).

It does imply that, it should be possible to contact the intelligence named Ayahuasca by ingesting the vine alone, or without ingestion. After all, what is contacting the plant spirit (plant consciousness) is your own spirit (consciousness). That has happened with me as well.

To followup: Marijuana, the plant material, should also house a plant spirit, with its own intelligence, knowledge base, and purpose. Likely, also responsive to songs that are related to it. And indeed, that has also been my experience with it too. I call that spirit by the Sanskrit name, Ganja, and tried it with the Sanskrit mantra.