What is "raphide"

n. (context biochemistry English) A crystal of calcium oxalate, shaped like a needle, which forms as a metabolic byproduct in some plant cells.

Raphides are needle-shaped crystals of calcium oxalate as the monohydrate or calcium carbonate as aragonite, found in more than 200 families of plants. Both ends are needle-like, but raphides tend to be blunt at one end and sharp at the other.