John Chrysostom

And why doth He not make it of things that are not? Stopping the mouth of Marcion, and of Manichaeans, who alienate His creation from Him, and teaching by His very works, that even all the things that are seen are His works and creatures, and signifying that it is Himself who gives the fruits, who said at the beginning, "Let the earth put forth the herb of grass," and "Let the waters bring forth things moving with living souls." For this is not at all a less work than the other. …

Homily on the Gospel of Matthew 49 ↗

Bede

And He said: Let the earth bring forth green plants producing seed, and fruit trees making fruit according to their kinds, whose seed is in itself upon the earth. And it was so. And the earth brought forth green plants, and bearing seed according to their kinds, and trees making fruit, each having seed according to its kind. And God saw that it was good, and the evening and the morning were the third day. It is clear from these words of God that the world's adornment was perfected in springtime. …

Commentary on Genesis (Hexaemeron) ↗

Bonaventure

"Let the earth bring forth vegetation: seed-bearing plants," etc. It has been explained how, by the gathering of waters, spiritual meanings should be understood. Now it remains to explain how the sacramental figures are symbolized by the vegetation of the earth. For it is not without reason that the vegetation of the earth is seen to point to Sacred Scriptures, in the sense that it has a great number of figures that grow and produce a multiplication of thoughts in the soul. Vegetation on earth is alive, generous, and lovely. …

Collations on the Hexaemeron, Collation 14 ↗