Waypoint 4: N32.01533 W112.70673)
Here the trail ascends a steep southerly-facing slope with a series of switchbacks. The view across the valley to the west includes Tillotson Peak, and the Bates Mountains with Kino Peak. Dominant plants here are jojoba (Simmondsia chinensis), brittlebush (Encelia farinosa), foothill paloverde (Parkinsonia microphylla) with occasional saguaros (Carnegia gigantea), ocotillo (Fouquieria splendens), Samo Prieto (Coursetia glandulosa) and Sangre de Cristo (Jatropha cardiophylla).
Looking to the west one can see a layer of yellowish welded tuff among the other layers of Tillotson Peak.
Waypoint 5: (N32.01522 W112.70598)
On the slope ahead to the east is an impressive stand of the Monument's namesake cactus. The main ridge of the Ajo Mountains looms up behind that. Visible is Mt. Ajo, at 4808 feet the highest point in the Ajo Mountains as well as all of Organ Pipe Cactus Monument. Dominant plants here are jojoba (Simmondsia chinensis), brittlebush (Encelia farinosa), and triangle-leaf bursage (Ambrosia deltoidea) along with foothill paloverde (Parkinsonia microphylla), saguaros (Carnegia gigantea), ocotillo (Fouquieria splendens), Samo Prieto (Coursetia glandulosa) and Sangre de Cristo (Jatropha cardiophylla).
Waypoint 6: (N32.01606 W112.70609)
At this point all around the trail is a dense stand of buckhorn cholla (Opuntia acanthocarpa). This cactus differs from the very similar staghorn cholla (Opuntia versicolor) by producing a brownish, dry shriveled up spiny fruit in contrast to the yellowish, fleshy fruit seen on the latter species. The distribution of staghorn cholla does not extend much farther west than the foothills of the Quijotoa Mountains on the way from Sells.
Waypoint 7: (N32.01735 W112.70569)
This point is at Estes Pass, a divide between Estes Canyon and the drainages to the south. From this point it is possible to see how Estes Canyon ends abruptly in a box canyon in the wall of the main Ajo Mountains ridge looming ever closer.
Along with the large organ pipe cactus here at the bench are buckhorn chollas (Opuntia acanthocarpa), saguaros (Carnegia gigantea), jojoba (Simmondsia chinensis), ocotillo (Fouquieria splendens), and Mexican tea (Ephedra aspera).