Responding rapidly to the recent rains, this Ocotillo is now covered with leaves. Photosynthesis requires a plant to open its stomata to allow in oxygen, which releases water. Plants often cease photosynthesizing to conserve water, with some like the Ocotillo taking extreme measures such as dropping their leaves entirely. The Ocotillo, rather than responding to seasonal clues that water may be coming, remains leafless until it actually rains, re-sprouting its leaves within a few days of rain, and dropping them again after a few weeks of drought.