Does an ethnobotanist study life or earth or physical science?

The best way to explain an Ethnobotanist's studies is to break down what the Word actually means.

Ethno being the study of ethics, and botan, (or botany) as the study of plants, so the best description for an ethnobotanist would be someone who studies the ethicical uses of plants in different cultures across the world.

some examples would be an anthropologist who studies different societies that use Ayauaska for spiritual experiences.