“The fact that some plants also cooperate towards each other’s preservation and generation is also evident from the following considerations. Among wild plants, deciduous ones cooperate with evergreens since when their leaves decay the earth is, as it were, fertilized which is useful for both good feeding and for the germination of their seeds; while among cultivated plants, those cooperate which people sow among their plants when they want to remove excess moisture from their vines, and among their vegetables either for this reason or because there is an infestation of bugs as bitter vetch is sown among radishes to guard against aphids and whatever else similarly grows among others. For we should assume these kinds of things happen among nature’s spontaneous creations, as well, especially if art imitates nature.”

ὅτι δὲ καὶ ἐν τοῖς φυτοῖς ἔνια συνεργεῖ πρὸς τὴν ἀλλήλων σωτηρίαν καὶ γένεσιν καὶ ἐκ τῶνδε φανερόν· ἐν μὲν γὰρ τοῖς ἀγρίοις τὰ φυλλοβόλα τοῖς ἀειφύλλοις ὅτι σηπομένων ξυμβαίνει καθάπερ κοπρίζεσθαι τὴν γῆν ὃ καὶ πρὸς εὐτροφίαν καὶ πρὸς τὴν βλάστησιν τῶν σπερμάτων χρήσιμον. ἐν δὲ τοῖς ἡμέροις ὅσα τοῖς φυτοῖς ἐπισπείρουσι τῶν ἀμπέλων ἀφαιρεῖν βουλόμενοι τὸ πλῆθος τῆς ὑγρότητος καὶ τοῖς λαχάνοις ἢ τούτου χάριν ἢ τῶν γινομένων θηρίων οἷον ταῖς ῥαφανίσι τοὺς ὀρόβους πρὸς τὰς ψύλλας καὶ εἴ τι τοιοῦτον ἕτερον ἑτέροις. οἴεσθαι γὰρ χρὴ τοιαῦτα καὶ ἐν τοῖς αὐτομάτοις τῆς φύσεως ὑπάρχειν ἄλλως τε καὶ εἰ ἡ τέχνη μιμεῖται τὴν φύσιν.

Theophrastus, Causes of Plants, 2.18.1–2