Crespian is a gender in the Nadurian System, one of the four Nature Systems. It is a gender which is both connected to nature and its overall aesthetics but which has a specific and strong connection to trees. One may feel like their gender is specifically related to trees, or they may feel that a certain aspect of their gender can relate to certain aspects of trees. For example, someone may feel that their gender is related to trees if their gender feels breezy, tall, and full of natural life and beauty. Crespian people can have any alignment and/or no alignment, and depending on what alignment they have, they could use another term from the Nadurian System to describe themselves. For example, a crespian person who is fiaspec could say they're rhosynic crespian, from rhosynian.
This gender is similar to, but not the same thing as, treegender. Because crespian belongs to a naturecoric alignment system, it consists of more than just a relation to trees: it encompasses a strong connection to nature as a whole, just with a specific focus on trees, whereas treegender people only feel specifically related to trees.