During walks with the dogs through our Louisiana neighborhood in January we noticed irregular balls of green leaves in tall trees that were otherwise barren. We eventually found a clump of this near enough to the ground to take a reasonable picture, and the ‘Picture This’ app identified it as oak mistletoe. Of course we are familiar with mistletoe because of Christmas, but had not realized that it grows locally.
Oak mistletoe (Phoradendron serotinum) is a hemiparasitic plant that generates some food on its own through photosynthesis, but also steals water and nutrients from its host. Heavy infestations of mistletoe can kill host tress.
The white berries of the oak mistletoe are mildly poisonous to humans, but are an important food for some birds. Birds spread mistletoe seeds from tree to tree, the seeds stick in tree branches thanks to a sticky coating called viscin. After germination, a structure known as the haustorium attaches the mistletoe to its host and taps into the resources of the host tree. The haustorium can be seen in the center image below, along with white mistletoe berries.