Annual growth layers in woody stems are produced by the .

Xylem

Explanation:  is a vascular tissue which moves water and nutrients from the roots to the leaves. Most woody plants form new layers of woody tissue each year, and so increase their stem diameter from year to year, with new wood deposited on the inner side of a vascular cambium layer located immediately beneath the bark.

im not intirely sure but i think the anwser is d relative humidity