Complex sentence: Finally, at the highest elevation elevations of the Tibesti, tree heath ("Erica arborea") grows from moist crevices formed by ancient lava flows, and 24 different species of moss provide substrate for the tree heath.
Split into simpler sentences: Finally, at the highest elevation elevations of the Tibesti, tree heath ("Erica arborea") grows from moist crevices formed by ancient lava flows. In addition, 24 different species of moss provide substrate for the tree heath.