What are "Sugar Leaves"?

I've seen this mentioned on a couple of posts, can anyone define what a sugar leaf is?

I'm two weeks into 12/12 in SOG set-up. Plants are only about 12" but the recent growth looks kind of like spinach. Dark green sort of crinkly leaves....

sugar leaves are the leaves that surround the bud that are covered in these crystals also. they look fuzzy with like little white hairs on them.