Saguaro after the rain

The saguaro is one of the largest cacti: according to the U.S. National Park Service, it can reach about 15 m in height. Its pleated, ribbed stem expands as it absorbs rainwater and contracts as the plant uses its stores. A shallow, spreading root system quickly takes up brief rainfall, while a waxy coating reduces water loss. Spines shade the surface and deter herbivores, but are not the main mechanism for conserving water.