The two Red Cedar trees next to our house not only serve to draw in birds passing through our yard, they also play host (literally) to some very interesting organisms. This morning, I looked out our office window and saw this:
Ahhh, it's an alien! Well, no, not really. It's actually a gall, caused by the fungus Gymnosporangium juniperi-virginianae. Galls appear when an insect or fungus feeds off of a plant and somehow changes the plant's structure, causing it to produce abnormal growths, inside of which the insect or fungus then lives. (For the tree, then, I guess this might actually count as an alien invasion.) Each gall-making creature has its own preferred host plant, and each causes a distinctive abnormal growth.
During the winter, these galls on our Red Cedar trees just looked like brownish balls -- they could have been windblown pinecones at first glance -- and it wasn't until recently that they sprouted these weird orange tentacles. (I only noticed them today.)
Those "tentacles" are actually the spore-producing appendages of the fungus inside the gall. According to this fascinating information sheet on cedar-apple rust (the "disease" caused by this fungus, so-called because the fungus actually needs to live on both cedar trees and apple trees in different stages of its life cycle), the tentacles (i.e., "telial horns") enlarge during periods of rainy weather, and indeed, with today's constant rain, the fungus was looking spectacularly goopy by the end of the day. (The gall in this next picture is the same one from the previous picture, but several hours later.)
I can see five of these galls from our window, and who knows how many more there are higher up in the trees. The fungus won't do lasting harm to the Red Cedars (these orange appendages mark the end of their life cycle), so our trees should be around for a while yet. Who knows what strange and interesting things these trees will show us next!