Glochids or glochidia are hair-like spines or short prickles, generally barbed, found on the areoles of cacti in the sub-family Opuntioideae. Cactus glochids easily detach from the plant and lodge in the skin, causing irritation upon contact.

What do glochids do?

The interesting thing about glochids is that they form to help the plant conserve moisture. They are actually modified leaves, unlike thorns, which are modified branches. Leaves like these prevent the plant from losing too much moisture in the form of evaporation. They are also a formidable defense strategy.

Do glochids go away?

While the long, nasty spines stay on the plant, glochids break off readily and work their way into the skin, causing itching and irritation that can, in sensitive individuals, last days, weeks or even months. ... But if you get any on your skin, the resulting rash is one you'll likely remember for a long time.