Adjectives

(a)radical, basalespecially of leaves; located at the base of a plant or stem; especially arising directly from the root or rootstock or a root-like stem“basal placentation”, “radical leaves”
(s)elementary, elemental, primary, basalof or being the essential or basic part“an elementary need for love and nurturing”, “a basal reader”
(s)basal, baseserving as or forming a base“the painter applied a base coat followed by two finishing coats”