17 I am going to bring floodwaters on the earth to destroy all life under the heavens, every creature that has the breath of life in it. Everything on earth will perish. 18 But I will establish my covenant with you, and you will enter the ark—you and your sons and your wife and your sons’ wives with you. 19 You are to bring into the ark two of all living creatures, male and female, to keep them alive with you. 20 Two of every kind of bird, of every kind of animal and of every kind of creature that moves along the ground will come to you to be kept alive. 21 You are to take every kind of food that is to be eaten and store it away as food for you and for them.”
- Genesis 7:1-4:
1 The Lord then said to Noah, “Go into the ark, you and your whole family, because I have found you righteous in this generation. 2 Take with you seven pairs of every kind of clean animal, a male and its mate, and one pair of every kind of unclean animal, a male and its mate, 3 and also seven pairs of every kind of bird, male and female, to keep their various kinds alive throughout the earth. 4 Seven days from now I will send rain on the earth for forty days and forty nights, and I will wipe from the face of the earth every living creature I have made.”
- Genesis 7:14-16:
They had with them every wild animal according to its kind, all livestock according to their kinds, every creature that moves along the ground according to its kind and every bird according to its kind, everything with wings. 15 Pairs of all creatures that have the breath of life in them came to Noah and entered the ark. 16 The animals going in were male and female of every living thing, as God had commanded Noah. Then the Lord shut him in.
- Genesis 7:20-23:
20 The waters rose and covered the mountains to a depth of more than fifteen cubits. 21 Every living thing that moved on land perished—birds, livestock, wild animals, all the creatures that swarm over the earth, and all mankind. 22 Everything on dry land that had the breath of life in its nostrils died. 23 Every living thing on the face of the earth was wiped out; people and animals and the creatures that move along the ground and the birds were wiped from the earth. Only Noah was left, and those with him in the ark.
I think it is quite reasonable to deduce from the above that God did not instruct Noah to bring plants and trees into the Ark. Furthermore, "every living thing on the face of the earth was wiped out". Now, even if the Jew did not consider plants to be living creatures, God knew that they are (because, well, they are). Thus, it is reasonable to think that if the Great Flood happened, all of the plants and trees died too. Even the aquatic plants died (presumably), because as the sea level rose, they were too far below it to capture sunlight to produce photosynthesis (plus the sky was covered in clouds). And yet, we read in Genesis 8:10-11, several days after the flood stopped:
10 He [Noah] waited seven more days and again sent out the dove from the ark. 11 When the dove returned to him in the evening, there in its beak was a freshly plucked olive leaf! Then Noah knew that the water had receded from the earth.
So, how come an olive tree did not die during the flood, if all the surface of the earth was under water for more than 40 days? Or is it that God repeated what He did in the third day of creation? Genesis 1:11:
Then he commanded, “Let the earth produce all kinds of plants, those that bear grain and those that bear fruit”—and it was done.