Lenticel
The lenticel is a porous tissue found in plants. The cellular structure has large spaces between the cells, which allow for gas exchange to take place. The bark of the tree is impermeable to gasses, so these gaps are what allow the gas exchange between the internal tissue of the tree and the atmosphere. The lenticels are a common feature used for identification of woody plants.
Mycelium
The fine white filaments of the fungus that generally live underground, and can be compared to a trees roots. The mushroom refers to the fruiting body of this root network, which sometimes can extend underground for 100’s of feet. In fact, the largest organism in the world is actually a honey mushroom fungus in Oregon that measures 2.4 miles wide!