Rashi: It is as if they were not planted. Radak - this shows how insignificant they will be - "v'Lo Noda Mekomo Ayam" (Nachum 3:17), "Im Yevale'enu mi'Mekomo v'Chichesh Bo Lo Re'isicha" (Iyov 8:18).

Malbim: They are like vegetation that was not planted via grafting or inserting shoots in the ground.

Rashi: Further, they will be uprooted, as if they were never seeded. Seeding is less than planting.

Rashi: When they are uprooted, the trunk will not take root in the ground to regenerate. Every other Shoresh in Tanach [is a noun]; the accent is on the first syllable, and there is a Patach (what we call Segol) under the Reish. Here, the accent is on the latter syllable, and there is a Kamatz (what we call Tzeirei) under the Reish; it is a verb.

Radak: It says "Af" three times - also us, also you, also our children. Giz'am is the trunk that is seen on the ground. What is under the ground is called Shoresh (roots). 'What comes from the Geza is of the buyer; from the Shoresh is to the land-owner' (Bava Basra 5:4).

Malbim: This rose by itself; it has no root, so it is very weak. It is prone to wilt and dry by itself.

Radak: They will be uprooted quickly, like the blowing of the wind. Nashaf is like "Nashafta v'Ruchacha" (Shemos 15:10).

Malbim: They themselves are weak, and additionally, a hard wind blew on them.

Radak: This is like Ru'ach Se'arah (a storm wind).