Making medicine with usnea can be tricky because you have to chop it up to get to the inside which is an important part of the medicine. But the same white chord poses a problem. It is touch and difficulty to chop finely when dry. However, DO NOT try and powder it or blend it, because the chord will bind your machine and may cause permanent damage to it. My favorite way of making usnea tincture for this reason is as a cooked tincture. Karen Aguiar has been known to use dry ice to freeze the usnea so that it can be broken down by being shattered in its cold state!
Usnea is a genus that includes several species of light grey green lichen. Sometimes there are little cups like the first image, but most of the time there are not. The KEY to identifying it correctly is the white chord in the middle (see image below to the left).
The two pages below are excerpted from Christopher Hobb's booklet 'Usnea: The Herbal Antibiotic '