Śaṅkaraon Brahma Sūtra 3.1.26

The conclusion arrived at under the preceding Siitra is confirmed also by scripture stating that the souls, after having entered into plants, ‘ become ’ beings performing the act of generation, ‘ for whoever eats the food, whoever performs the act of generation, that again he (the soul) becomes.’ Here again the soul’s ‘becoming ’ he who performs the act of generation cannot be taken in its literal sense ; for a person becomes capable of generation a long time after his birth only, viz. when he reaches puberty. How then should the soul contained in the food eaten enter into that condition in its true sense ? Hence we must interpret the passage to mean only that the soul enters into conjunction with one who performs the act of generation ; and from this we again infer that the soul’s becoming a plant merely means its entering into conjunction with a plant.