Raphides are needle-shaped crystals of calcium oxalate as the monohydrate or calcium carbonate as aragonite, found in more than 200 families of plants.

Raphides in Palm Embryos and their Systematic Distribution
The acridity of raphides from the edible aroids
Raphides with barbs and grooves in Xanthosoma sagittifolium (Araceae).
Twin Raphides in the Vitaceae and Araceae and a Model for Their Growth
Twinned raphides of calcium oxalate in grape (Vitis): implications for crystal stability and function
Development of idioblasts and raphides in the aerial root of Monstera delicosa liebm
[Comparisons of crystal form of raphides to toxicity raphides in four poisonous herbs of Araceae family]
A third type of raphide crystal in the plant kingdom: Six-sided raphides with laminated sheaths in Agave americana L
Starch structure and some properties of cocoyam (Xanthosoma sagittifolium and Colocasia esculenta) starch and raphides
Irritant contact dermatitis caused by needle-like calcium oxalate crystals, raphides, in Agave tequilana among workers in tequila di...