That’s a great idea—cacti are like nature’s tiny water banks. Their stems are thick, spongy, and have a high cellulose-to-lignin ratio, which lets them soak up and hold water without losing too much through evaporation. The shallow, wide-spreading roots catch rain quickly, and the areoles on the stems have stomata that close tightly when the air is dry. If you dig into the physiology, you’ll find that their mesophyll cells can swell up to ten times their normal volume, which is amazing for a plant that lives in the desert. We could look at how their cell walls are structured or how they regulate ion transport during drought. Let me know which angle intrigues you most.