Let’s Get Thermonastic

Or, Thermonastic Leaf Movements in Evergreen Rhododendron. In wintertime, rhododendron leaves point downward and curl up lengthwise like cigars–an adaptation to protect the plant from extreme temperatures. As temperatures rise, the leaves uncurl, flatten and angle upward to catch more sunlight. This reaction to temperature is called thermonastic movement. I first noticed it in the Blue Ridge Mountains’ native Catawba Rhododendron (Rhododendron catawbiense), shown here.

Traditional media on paper. Typeface inspiration James Todd’s Unit Gothic. The three simple characters worked perfectly together.