As nouns the difference between irritant and glochid
is that
irritant is any medication designed to cause irritation while
glochid is a form of small, detachable, irritant spine occurring in dense clusters in the areoles of certain cacti such as prickly pear. Typically glochids are short, straight, and microscopically barbed. When stuck into the skin of anyone touching the plant, they detach and remain in the skin when the victim moves away.
As an adjective irritant
is causing irritation or inflammation.