SAGUARO - THE GIANT CACTUS

SAGUARO CACTUS

Genus: Carnegiea
Species: Carnegiea gigantean
Family: Cactaceae
Class: Magnoliopsida, Dicots
Average Height: 30 feet

GEOGRAPHICAL LOCATION

LOCATION:

Found especially in a rocky terrain of a desert, the Saguaro Cactus is mostly found in the hot, dry climate of Sonoran Desert in the south-western part of North America. It is common in south-west of Arizona, south-east of California anad in the Sonoran state of Mexico.








GENERAL ADAPTATIONS:

SPINES ON THE STEM

The saguaros with their structural modifications are well-adapted to the natural conditions provided by the Sonoran Desert. The thick epidermis and waxy cuticle of Saguaro prevent loss of water by transpiration. So the transpiration only takes place by the stomata, when are open. The two-inch spines located on the trees vertical ribs protect Saguaro from the desert animals which would otherwise use it to meet their water requirement. Even the spines protect the sensitive tip of the plant from extreme heat or cold. The Saguaros have more numbers of parenchyma cells than other plants to help water retention. The stem of the plant can be 18 to 24 inches in diameter which can soak and hold a lot of water (in a toxic form) when it rains. This stored water helps not only in photosynthesis, but also protects the plant from the extreme heat. The heat absorbed by the plant during day is stored in the interior parts of the stems and the stored water does not allow this heat to spread upto the leaves due to low specific heat of water. At night this heat is released out which, in turn, prevents the plant from freezing in the chilled nights.

AMAZING ROOT SYSTEM OF A SAGUARO:

The root system of the plant is thinner considered to its size and weight. It has one tap root which grows only three feet. Two sets of radial roots spread out. One is thicker which is only about one foot deep and the other thinner set is as long as the plant itself. 

SPECIAL ADAPTATION:

RIBS ON THE STEM

A special adaptation of the plant is the pleated rib system on its stem. The ribs unfold its pleats and expands almost 25% of the original size of the plant while it is absorbing water, thus preventing the plant from bursting. When the water is used up, again the ribs fold up and shrink. This allows the Saguaro to be almost 90% water. Thus a matured Saguaro weighs more or less 6 tonnes.

FLOWERS OF SAGUARO

CO-EVOLUTION:

The Saguaro homes many bats, wasps, butterflies, ants and bees and also feed them with its nectar.

GILA WOODPECKER

The Gila Woodpecker has a mutual relationship with this cactus. The Gila Woodpecker holes the plant for nesting as it can not find any other suitable tall and woody plant for staying in the midst of the Sonoran Desert. Moreover the holes are made in the older and harder sections of the plant between the epidermis and the ribs without causing any harm to the cactus. Rather the Woodpecker can eat up the damaged parts of the plant or the other insects causing harm to the plant. In turn, the Saguaro creates a hard casing of scar tissues called callous, which detach the bird's nest from the rest part of the plant.

ILLEGAL POACHING OF SAGUARO

HUMAN INTERFERENCE:

In recent times, a black market has evolved in Arizona, where the poachers can easily make a few thousand dollars of the sale of Saguaro. however, it is still not endangered as the USA government has taken some positive steps in rescuing this rare species. There is a national park called Saguaro National Park for protecting the plant from poachers.