Basal

I'm keeping a record of basal body temperature.

This is the basal idea.

The organism needs more energy on basal maintenance.

A basal reader is a kind of book that is used to teach reading.

In the spring, basal leaves emerge from a stout taproot.

a basal diet

Hittite is a basal Indo-European language.

A magnolia is a basal angiosperm.