This is really curious, and seemingly strong evidence that the author must know that he is not speaking of observable reality. This definitely sounds like the plain old vegetation such as any of us would expect. However there is something significant here in terms of the metaphysical picture that I don't grasp. This is definitely bizarre. Though I don't understand the significance, I know that the sun and moon and stars are used metaphorically throughout the Scripture.
Metaphysical authority is a significant issue throughout the Scripture.
Here heavens is the skies, and the waters are the waters. Though definitely a new metaphysical stage in creation, most of what I saw as metaphysical language is now used to describe the physical. So here on the sixth day, the stage of animals being given dominion over the dry land arrives. He created them. And God saw all that He had made, and behold, it was very good.