This is what they are in the Old Testament, they were not literal trees or grass then, so why do so many think that they should be literal in the New Testament?
7 The first angel blew his trumpet, and there followed hail and fire, mixed with blood, which fell on the earth; and a third of the earth was burnt up, and a third of the trees were burnt up, and all green grass was burnt up. Rev. 8:7
The Trees are People
When the house of David was told, “Syria is in league with Ephraim,” his heart and the heart of his people shook as the trees of the forest shake before the wind. Is 7:2
“For you shall go out in joy, and be led forth in peace; the mountains and the hills before you shall break forth into singing, and all the trees of the field shall clap their hands. Is 55:12,
. . . to grant to those who mourn in Zion — to give them a garland instead of ashes, the oil of gladness instead of mourning, the mantle of praise instead of a faint spirit; that they may be called oaks of righteousness, the planting of the LORD, that he may be glorified. Is 61:3
11 Then I said to him, “What are these two olive trees on the right and the left of the lampstand?” 12 And a second time I said to him, “What are these two branches of the olive trees, which are beside the two golden pipes from which the oil is poured out?” 13 He said to me, “Do you not know what these are?” I said, “No, my lord.” 14 Then he said, “These are the two anointed who stand by the Lord of the whole earth.” Zech 4:11-13
Green Grasses are Living People or God’s People.
Thou dost sweep men away; they are like a dream, like grass which is renewed in the morning: 6 in the morning it flourishes and is renewed; in the evening it fades and withers. Ps 90:5-6
. . . the waters of Nimrim are a desolation; the grass is withered, the new growth fails, the verdure is no more. Is 15:6
A voice says, “Cry!” And I said, “What shall I cry?” All flesh is grass, and all its beauty is like the flower of the field. 7 The grass withers, the flower fades, when the breath of the LORD blows upon it; surely the people is grass. 8 The grass withers, the flower fades; but the word of our God will stand for ever. 40:6-8