wax tree, sumac
枦 centers on a specific tree or its product: the wax tree or sumac, a plant used for its waxy coating or other practical purposes.
枦 combines 木 (tree) with 户, which likely contributes the sound ロ. The character was created to name the wax tree or sumac.
A tree 木 beside a door 户: imagine a wax tree growing right outside the door, its leaves coated with natural wax.
For ロ, picture a row of wax trees planted in a neat row outside the door: row -> ロ, and the trees produce wax.