Commentary
The word: شَجَر (shajar) in Verse An-Nahl 16:10 ⧉ مِنْهُ شَجَرٌ فِيهِ تُسِيمُونَ (from which [ you grow ] plants, on which you pasture cattle) is mostly applied to a tree which stands on a trunk. Sometimes, it is also applied, in an absolute sense, to everything which grows on land. Included therein are grass on stems or tendrils. This is the sense meant in this verse, because the pasturing of cattle has been mentioned immediately after which is mostly related to grass.
The last word: (tusimun) is a derivation from isamah which means to leave cattle to graze freely in a pasture.