Those are some beautiful roots! That's awesome. What kind of tree is that? After you posted those photos of the
Encyclia mounted on the Floss Silk Tree, I mounted some NOID Cattleyas to my Floss Silk Tree. The roots have attached themselves nicely.
Lately I've been trying to figure out just how much tree transpired water an orchid can absorb when it is mounted on a tree. According to the
wikipedia article on transpiration, a full grown tree can lose
several hundred gallons of water through its leaves on one hot day. That's a lot of water.
Leaf transpiration, an important part of photosynthesis, occurs through stomata. I'm guessing that because your trunk is somewhat green that photosynthesis is occurring and that stomata are present. Not sure at what density stomata occur but I picture the orchid root being able to absorb some of the moisture that is being released by the stomata around it and perhaps under it as well. Logically, the fatter the root the more stomata it will cover.
Practically speaking, all things being equal, an orchid mounted on a photosynthetic trunk might need somewhat less water than an orchid mounted on a non-photosynthetic trunk. Wish I knew exactly how much less water.
Perhaps if there is anybody that took a botany class they can elaborate on the plausibility of my theory.
Swamper 
Threaded Mode
