Yesterday's mystery plant was kind of a corker.
Youngchick2000 wrote me saying she thought it was a "Swamp Willow"... she was halfway there.
It is actually a type of "gall" or growth on willows called, a “Pine-cone willow gall” and is caused by a gall midge, (of course, hits forehead with heel of hand) Rhabdophaga strobiloides. (Which is kinda fun to say)
This dipteran (related to flies and mosquitoes) deposits an egg in the developing terminal leaf buds of the willow in early spring. The larva releases a chemical which interferes with the typical leaf and branch development of the willow, instead causing the formation of this cone-like structure. The adult dipteran emerges the following spring, after having spent the winter in the gall. (Spring, Summer, Winter, & Gall)
The thing that threw me especially was that it grows on the tip of the stems, and I've always had this vision in my head of galls being a side or hanging growth sort of thing. Leave it to nature to always sneak a curve ball in there.
Check out a few more photographs of pine-cone willow gall via the Cornell Plant Pathology Herbarium or read more about galls courtesy of the Michigan Entomological Society.
Whew! I can sleep tonight!