18. Brownpitaya (_Echinocereus chloranthus_) is one of the so-called rainbow cactus group. Notice the banded color separation of the short needles. The small brown flowers grow around the plant in large numbers during the bloom period. Another variety, which grows at low elevations in the park, has yellow-orange blossoms reaching a diameter of 4 inches. 19. Mountain-Mahogany (_Cercocarpus eximius_). The wood is extremely hard, so brittle that it may be broken very easily. Deer browse on the leaves, and, outside the park, cattle and sheep feed upon it. 20. Lichen. Raise your eyes to the exposed barren escarpments of Casa Grande and other rock outcroppings. Here you observe greens, blacks, and other colors. Much of this color may be attributed to the lichens (LYK-ehnz) encrusting the bare rock surfaces. The small colorful organisms are the first visible signs of life to gain a foothold on rocks. Without true roots, this little “mutual” obtains moisture from the atmosphere. A lichen is actually a fungus and an alga living together in mutual dependence (one provides board and the other room for both). As a product of their life processes, carbonic acid is formed. This slowly disintegrates the rock, helping to form soil, thus aiding in the production of suitable living conditions for higher types of plants. 21. Ash (_Fraxinus_ sp.). Ash has long been identified as a very useful wood; even the early Indians utilized it for paddles, bows, arrows, etc. The winged seed resembles a small canoe paddle. 22. One-Seed Juniper (_Juniperus monosperma_). There are four junipers found in the park. (You have already seen two of the others along this trail.) This one is so named because it has but one seed in each berry. Junipers (often miscalled cedars) are distinguished from other cone-bearers by the seeds being enclosed in a berry instead of a cone. The wood is resistant to decay and used much for posts. Of course, in a National Park, trees are preserved for their scenic and watershed protection value and are not harvested for commercial purposes. 23. Another picture just ahead—Striking view of Juniper Canyon. _Help Protect the Park from FIRE Please Smoke Only in Designated Areas_ ORIENTATION POINT As an inducement for hikers desiring to continue farther along this trail, an orientation table has been constructed about 1½ miles beyond this point. The table points out the major landscape features together with their elevations. From the same general area, a spectacular view of the rugged Big Bend country may be enjoyed. GEOLOGICAL SIGNIFICANCE Millions of years ago, the ocean which extended from the Gulf of Mexico to the Arctic Circle covered this part of west Texas. Muds, sands, and gravels were deposited in the bottom of that ocean. In these sands and gravels were preserved the remains of fish, shellfish, and various other forms of sea life.