What: With my last post on poison ivy, I wanted to return to another good friend of mine: jewelweed (Impatiens capensis). In Centennial Woods, we only have spotted jewelweed (the yellow-flowered pale touch-me-not is found on much richer sites). I spent some time observing it while watching the hummingbirds, admiring its simple elegance. The flowers are so rich and ornate, with no shortage of suitors begging nectar. It grows abundantly anywhere there's water so I headed down into Centennial Woods below the sandy slopes and found a great patch to take some photos.
Minute hairs on the surface of the leaves trap air and cause water to bead on the surface. When you hold a jewelweed leaf underwater it seems to transform miraculously into silver! These leaves were holding some of that much needed rain from last night. Many other plants do this too, and since it's a pattern we have to have a super cool esoteric word for it: superhydrophobicity (really afraid of water!! aka the lotus effect). Some plants achieve superhydrophobicity by having a dense coating of bristly hairs, others, like lotus, have waxy cuticles. Supposedly this is linked with both water retention as well as being able to wash leaves clean, even with dew. Since the water beads up it has a high internal charge and will pull dust and other stuff off the leaf surface.
Yesterday I was noting that many had the malformed flowers, or galls. Inside that green blob there's a Jewelweed gall midge (Schizomyia impatientis). They hatch early fall and overwinter as adults.
Where: There's a great patch of the spotted kind in CW where an intermittent stream drains off the slope (it's been dry most of the summer though) and you can follow the flow of the water by where the jewelweed grows. Jewelweed definitely prefers wetter areas. So when you find poison ivy, often times walking downslope or finding a drainage will yield a good patch of jewelweed.