There are a lot of plants with extremely wavy leaf margins and ruffled leaves are hard to draw.
It's possible some of the more symbolic-looking shapes are inspired by nature or that they serve a dual purpose (naturalistic and symbolic).
Kalanchoe or Bucephalandra are examples of plants that might inspire nebuly-like leaf margins. There is one species of that specifically has a nebuly-like margin (it is both indented and ruffled in a smooth regular way) but I can't remember the name of the specific species. Ruffles kale might also be drawn that way by someone who wanted to get the idea across but in a simplified way.
It's possible some of the more symbolic-looking shapes are inspired by nature or that they serve a dual purpose (naturalistic and symbolic).
Kalanchoe or Bucephalandra are examples of plants that might inspire nebuly-like leaf margins. There is one species of that specifically has a nebuly-like margin (it is both indented and ruffled in a smooth regular way) but I can't remember the name of the specific species. Ruffles kale might also be drawn that way by someone who wanted to get the idea across but in a simplified way.