This group consists of leaves normally grown near the bottom of the stalk. Leaves of the X group usually have a blunt tip and open face; they show some ground injury characteristic of the group.
Code of Federal Regulations
[42 FR 21092, Apr. 25, 1977, as amended at 48 FR 29671, June 28, 1983; 49 FR 16756, Apr. 20, 1984; 51 FR 25028, July 10, 1986]