Like all members of the carrot family, the inflorescence of yampah,
perideridia gairdneri, forms a compound, flat-topped umbel, the individual clusters themselves branched and containing several dozen tiny white flowers. Leaves around the base are large, finely divided and often wither by flowering time; those further up the (solitary) stem are smaller and simpler. The tuberous roots are fleshy and edible, cooked or raw, and have several medicinal benefits.