text: It occurs in tree fern fronds, a specialty called fiddlehead (furled fronds of a young tree fern in the order Cyatheales, harvested for use as a vegetable). These fronds are edible, but can be roasted to remove shikimic acid.
  Shikimic acid is also the glycoside part of some hydrolysable tannins. The acid is highly soluble in water and insoluble in nonpolar solvents, and this is why shikimic acid is active only against Gram-positive bacteria, due to outer cell membrane impermeability of Gram-negatives.