Tell true cacti from Euphorbia look-alikes quickly and safely using areoles and latex clues.
Areoles define cacti
Cacti show discrete areoles where spines and flowers emerge (e.g., Mammillaria spinosissima). Euphorbias lack areoles and bleed milky latex when cut (e.g., Euphorbia trigona).
Reading stems
Cacti often have ribs or tubercles with areoles along each ridge; Euphorbias have angled, winged stems with paired thorns at edges.
Handling notes
Protect skin and eyes from Euphorbia latex; wear gloves and sterilize tools after pruning.
