In the Arizona Upland portion of the Sonoran Desert, the plant that commands most of the attention is the iconic Saguaro with its tall stature and dramatic form. In moving from the desert valleys toward the surrounding higher terrain, the plant community becomes increasing dominated by grasses and presents a decidedly low stature aspect. There is one plant, however, that towers over its neighbors in these vast arid grasslands in much the same way as the Saguaro dominates the desert valleys. In southern Arizona that plant is the Soaptree Yucca (Yucca elata). Other species of Yucca replace it in other regions of the grasslands. They, like the Soaptree Yucca, can become quite massive and grow to a height of fifteen feet or more, and can be seen standing tall in the sweeping mid-elevation seas of grass.
If you examine a sufficient number of individual Saguaros, eventually you will encounter a “cristate” specimen. Cristate, or crested, Saguaros display abnormal growth patterns, most often wildly fan-shaped. The condition that causes this aberrant growth in Saguaros (as well as in other plants) is called fasciation, and it occurs quite rarely. This means that the discovery of one of these unique cacti is an exceptional find indeed.
This photograph was taken in Saguaro National Park’s eastern unit in the foothills of the Rincon Mountains. The large Saguaro (Carnegiea gigantea) in the foreground is notable for having multiple trunks.
The sun sets on a gnarled Pinyon Pine (Pinus edulis) on the edge of the Grand Canyon, Arizona.
When a woodpecker excavates a nest cavity in a Saguaro (Carnegiea gigantea), the cactus responds defensively by sealing off its living tissue and produces a protective callus material heavily impregnated with lignin. As it continues its excavation, the bird first drills an entry hole into the cactus and then turns downward to hollow out a space for its nest. This results in a boot-shaped callus-lined cavity. When the Saguaro dies, the softer fleshy tissues rots away, leaving behind the woody ribbed skeleton of the Saguaro as well as any “boots” created by nesting woodpeckers. This Saguaro boot was found amid the woody ribs of a long dead Saguaro in the Rincon foothills of Arizona.
In certain ideal sites, Saguaros can grow in stands of increased density in response to the favorable conditions. Here, in this photograph from Sabino Canyon in the Santa Catalina Mountains of Arizona, the favorable conditions once included the the presence of a large Palo Verde that served as a nurse tree for this tight “quorum” of Saguaros. The Palo Verde is long dead now that the big cacti are all grown up. The only evidence of its existence is the tangle of trunk and branches strewn about the bases of the Saguaros, along with the dense stand of cacti it helped nurture that we see today.
The California Barrel Cactus (Ferocactus cylindraceus) is one of three species of barrel cactus found in Arizona. As is the case with its relatives, it has a spherical shape early in its life. It assumes a more columnar aspect as it grows, however, and can grow to over six feet tall. This one was photographed in Maricopa County, Arizona near Stewart Mountain.
The Cane Cholla (Cylindropuntia imbricata) is a species of cactus known for being relatively cold hardy. For this reason, they are often found in the desert grasslands of the Southwest where there are few other species of cactus due to the cooler environment. This one was photographed at about 4,400′ in elevation on the J-Six Ranch in Cochise County, Arizona.
The White and Lavender Columbine (Aquilegia cerulean), also known as the Rocky Mountain Columbine, is the state flower of Colorado. These were photographed in Imogene Basin in the San Juan Mountains, Ouray County, Colorado.
Many species of Manzanita are present in western North America ranging from Canada to Mexico. They are characteristic plants of a habitat, or biome, called chaparral. Manzanitas are evergreen shrubs or small trees with interesting smooth reddish, almost polished-looking bark. At mid-elevation locations in Arizona, the local chaparral biome is more simplified and is referred to as interior chaparral. These Manzanitas (Arctostaphylos pungens) were photographed at about 6,800′ in the Santa Catalina Mountains of Arizona.