Changes in stool color alone do not cause symptoms. The underlying cause of the change in stool color, texture, or form is responsible for any symptoms. Bowel movements are usually light to dark brown in color, and there is moderate variation among individuals with respect to stool color, quantity and form.
Plants in the Twilight Zone As the amount of light decreases, the size and complexity of plant life also decreases. So whereas there may be flowering plants growing in the entrance zone, the twilight zone is typically marked by mosses and ferns.
Now numerous leguminous plants occur in this desert, with nitrogen-fixing Rhizobium in their root nodules. Examples are the green-stemmed brush-like trees at the right and left of the image (Parkinsonia species, common name paloverde), and several acacias and mesquites (not seen in this image).