Adjectival form of "phyllid?"

Phylliform is the adjectival form of the very similar word phyllidium, which was truncated to form phyllid. OED, "phylliform, adj.":

Leaf-shaped, leaflike.

Rather like foliate is used far beyond botany to describe leaf-like things, phylliform is also used to describe anything sufficiently leaf-like, like anatomical features that are shaped like leaves.