Cactus, Trees and Shrubs of the Desert Preserves

Saguaro Cactus 

Saguaro is the keystone plant and icon of the Sonoran Desert. This slow growing columnar cactus is this country's largest cactus, often reaching between 40 and 60 feet in height and weighing (when fully hydrated) approximately 80lbs per foot. A mature Saguaro may weigh as much as 8 tons. They can live for more than 200 years. The State Flower: Saguaro flowers are formed on the growing tips, and following pollination, fruits will form, each containing approximately 2000 seeds. Dispersal, rainfall, and other factors result in only about one mature plant per 40 million seeds. ^ ^^

 Saguaro Cactus bloom

 
Palo Verde tree  

In 1954, the State of Arizona named the Palo Verde as its State Tree. The legislature did not distinguish between the two species of this tree (the foothills and the blue) that are native to the State; therefore both the Foothill and the Blue share the honor. Both the Blue and Foothill Palo Verdes have a number of characteristics in common, starting with the reason they are called Palo Verdes (Spanish for green stick).  Palo Verdes serve as the nurse plants for the saguaro, giving shade and protection to seedlings in their slow growth to becoming giants. Plant diversity encourages diversity of animals attracted to the food, shelter, and nesting sites provided by Palo Verde trees. ^^^^  ^^^^^

 

Teddy Bear, or Jumping Cholla

Teddy Bear or Jumping Cholla Cactus
Have an upright trunk with closely spaced horizontal branches near the top of the trunk. The stems are protected by a dense covering of yellowish spines which makes this cactus look soft from a distance, hence the common name Teddy Bear. This covering of spines not only provides protection from herbivores like rabbits and rodents, it also is believed to protect the stems from intense sunlight and may be a cooling mechanism for the cactus. The spines are very sharp and well barbed. Younger spines are yellowish and turn black with age. Yellow-green flowers emerge at the tips of the stems in spring, and the fruits that follow usually have no viable seed.  The segments of the Teddy Bear Cholla are easily detached from the plant by a soft touch of a passing animal or human, or even by strong winds. Many people might swear that the cactus jumped at them and grabbed them, which explains the common name, Jumping Cholla. ^ ^^^^^^ (Click Cholla image to  view larger)

Creosote Bush

Medium to large sized shrubs. Often several seemingly distinct shrubs will be growing together in a ring 6 to 20 m in diameter. This represents a clone of an original plant that may have been growing continuously for thousands of years. Small compound leaves are shiny, resinous, and dark green when young but can remain on shrubs for extended periods turning almost brown but still viable. The resin odor is at once acrid to deter plant eaters and yet pungently pleasant. The whole desert takes on this heavenly aroma after a rain shower signaling a return of life and verdance. No thorns. Yellow flowers with five petals appear generously in spring and at almost any other time of year following periods of generous rainfall. ^^^^^ 

Tringle-leaf Bursage

Triangle-leaf bursage is a densely-branched subshrub to about 2 feet (0.6 m) tall with triangular, finely toothed, gray-green leaves. The leaves are lost in very dry periods. Though it can be confused with brittlebush when not in flower; this bursage is a smaller plant with smaller, duller gray leaves. It flowers from late winter into spring, with burs ripening in late spring. Triangle-leaf bursage has small, 1/4 inch wide yellow-green flowers without petals. They grow in pairs from the end of growth spikes and flower from February to July. Bursage gets its name from its burr-like seeds. The round seeds are covered with hook-tipped spines that attach themselves to the fur of passing animals. The plants produce many seeds after both summer and winter rains. Triangle Leaf Bursage is a member of the ragweed family. It is native to the Sonoran desert and is one of the most commonly encountered plants in South Mountain and McDowell Mountain Parks. 

Desert Globe Mallow

Desert Globe Mallow 

Globe Mallow is a perennial native to the Sonoran Desert. This resilient plant is shaped like a rounded shrub and can survive in temperatures from 5 degrees and up. To live it requires full sun and as a result can grow very fast, up to 3 feet tall and 3 feet wide. As an Evergreen it has a gray/green color and a coarse texture. Its flowers bloom in spring and can be orange, white, pink or lavender. Be careful when touching while hiking in Phoenix, it has no thorns but can irritate skin and eyes. ^^^^^ (Click to enlarge this Globe Mallow found on the Mormon Trail in South Mountain Park)

 

Brittlebrush

Brittlebush
Brittlebush is a medium-sized rounded shrub. Plants grow 2-5 feet high. It has long, oval, silver-gray leaves that are somewhat fuzzy. The branches are brittle and woody, and contain a fragrant resin. In the late winter and early spring small yellow flowers form on long stalks well above the leafy stems. The hairs on the brittlebush plant serve several purposes. Many desert plants have hairy leaves or stems. The hairs act like a blanket over the leaves to protect them from the heat and cold. The white color reflects the sunlight helping to keep the plant cool. They also help trap any moisture and reduce the amount of water lost. ^^^ ^^^^^ (Click on image of Brittlebrush to see the details)

 

References and Links

^ National Park Service http://www.nps.gov/grca/naturescience/plants.htm

^^ Arizona-Sonora Desert Museum http://www.desertmuseum.org/visit/

^^^ Arizona Naturalist http://arizonensis.org/sonoran/fieldguide/plantae/encelia_far.html

^^^^ DesertUSA http://www.desertusa.com/mag01/aug/papr/palov.html

^^^^^ Sonoran Desert Naturalist http://www.arizonensis.org/sonoran/places/southmountain.html#Shrubs

^^^^^^ The Living Desert http://www.livingdesert.org/desert_plants_page.html?latin_name=Cylindropuntia+bigelovii