"Cold Weather Indicators"

Since I live in Wisconsin we have temperature extremes and I am also a gardener.  I have made an observance of a rhododendron plant in my garden. This rhododendron plant keeps it's leaves all year long. My husband and I can tell if it is really cold outside just by looking out our front window at this plant. When the weather is mild (above freezing ) the leaves on the plant are flat and spread out, but when it is very cold they curl up tightly and do not look very happy. Just thought this was interesting :)