Horizontal Arm Spur System Small 320×227 Medium 640×455 Large 1024×728 Download TIFF Original 2400×1706 | (873.6 KB) Description A diagram of the horizontal arm spur system, depicting the various parts of a vine. Keywords arm spur system, grape, grape vine, grapevine, horizontal arm spur, horizontal arm spur system, Vineyard Galleries Pruning Source: Government Printing Office Yearbook of the United States Department of Agriculture (Washington, D.C.: Government Printing Office, 1897)