Hypogymnia Imshaugii

Day 130: The Hypogymnias are collectively known as "tube lichens" for reasons which become obvious if you look at them closely. Their lobes appear inflated and in fact are hollow. The upper surface is greyish-green, separated by a distinct dividing line from the black lower surface. The apothecia are generally large when present, making the genus fairly easy to identify in the field. Determining species gets a little trickier, but H. imshaugii (Forked Tube) has a characteristic which sets it apart from its look-alikes. If you pull one of imshaugii's slender lobes apart to examine the inside, it will reveal a white medullary ceiling, which is to say that the inside of the top side is white. H. heterophylla, H. inactiva and H. enteromorpha all have black or dark medullary ceilings. Other species of Hypogymnia may have broader lobes, pinched lobes, holes at the lobe tips. These are all features to take into consideration when trying to identify them.