Cult of the Witch Queen — Richard S. Shaver

This is a tale of two planets, Earth and Venus, and of a man who found himself the plaything of the ugliest and oldest woman on the two worlds. She looked like a witch, and a capable witch has spells. This witch had had six centuries to study the ancient magic: the incredibly antique mechanisms left by the race whom we remember in vague myths only as--the Gods. One day I met a man who told me this story. Knowing as I do that the antique caverns and the ancient mech of the God race does exist; knowing that trees are rejuvenated by the grafting on of young trees, I could not help but see the possibility of the truth of this story. That children can be grafted on to aging people, and the young sap, the vital growth secretions of their bodies, used to make the modern vampire life on and on. Originally published in Amazing Stories in August 1946.