The purpose of this experiment was to discover why Rosebay Rhododendron leaves curl in cold and drought. Six different leaves were tested in three trials, with two leaves per trial. The leaves were placed in an environment with increasingly cold temperatures. Their width was recorded in metric measure at a fixed place on the leaf at select temperature intervals. The different temperatures used were +5, 0, -5, -10, and -17 degrees centigrade. Pictures were taken with a Polaroid camera at +5, -5, and -17 degrees centigrade. Of the six leaves tested, three were large leaves and three were small leaves. After being subjected to -17 degree temperatures, the average amount of curl for the small leaves was 64.3% of their normal width. The average amount of curl for the large leaves was 65.6% of their normal width. The average amount of curl for all the leaves was 65% of their normal width. The hypothesis that the leaves curl to protect the stomata was rejected, because the experimenter was not able to conclusively prove it. There are several theories as to why these results could have occurred, but the actual cause of curling has not been discovered. This experiment has practical uses because the leaves could be used to tell approximate temperature at or below +5 degrees centigrade.