Saguaro
Carnegiea gigantea
Carnegiea gigantea is the only species of the monotypic genus Carnegiea in the cactus family ( Cactaceae ). The botanical name honors the American industrialist and philanthropist Andrew Carnegie. The specific epithet refers to the large natural height of the type common names are " Saguaro " and " Sahuaro ".
- 5.1 Literature
- 5.2 Notes and references
Description
The plants are very large, columnar stem succulents with a very shallow root system and few branches formed only at an advanced age. The main shoots are about 12 to 15 m ( in some cases up to 20 m) tall and 30 to 70 cm thick. The standing several meters in height branches are maintained. The standing on the twelve to 24 rounded ribs brown areolae among themselves at a distance of about 2 to 2.5 cm. The areoles spring twelve or more, 1 to 2 cm long, radiating arranged spines and three to six strong, to 7 cm long central spines. In the height of the plant the gray spines are shorter and finer.
The flowers formed by the crest near areolae are 8-12 cm long and open yourself up to a diameter of 12 cm. Your bracts are white to cream-colored. The fruits formed after fertilization are 6-9 cm long, outside felted weak and carry on the areoles sometimes one to three thin thorns. At maturity, the fruits are red inside and out and flip from the tip on. The very many (up to 4000), about 2 mm large seeds are black.
Dissemination
Carnegiea gigantea is in the United States in the state of Arizona, as well as in the south of the State of California west of the Colorado River and disseminated in the Mexican state of Sonora in the Sonoran Desert at an altitude 180-1350 meters.
Particularly large stocks are in the highlands of Arizona and near Tucson and Saguaro National Park.
System
Outer systematics
The genus Carnegiea is classified within the cactus family in the tribe Pachycereeae. Molecular genetic studies showed that the genus Carnegiea is closely related to the genus Pachycereus:
Carnegiea
Pachycereus
Cephalocereus
Pseudomitrocereus
Marshallocereus
Backebergia
Lophocereus
Pterocereus
Lemaireocereus
Inside systematics
George Engelmann struck in 1848 before the provisional name Cereus giganteus. The first description was followed four years later. Nathaniel Lord Britton and Joseph Nelson Rose set the style in the new genus Carnegiea.
A synonym of the genus is Rooksbya ( Backeb. ) Backeb. Synonyms of type Pilocereus giganteus ( Engelm. ) Rümpler (1886 ) and Pilocereus engelmannii Lem. (1862 ).
Ecology
The heyday at the locations of the plants is from May to June, just before the rainy season. The flowers open about two hours after sunset and then stay open until noon the next day. The pollinators are in addition to some insects the flowers bat Leptonycteris curasoae and birds such as the dove Zenaida asiatica, the hummingbirds Calypte costae, Archilochus Alexandrian and Cynanthus latirostris, the Trupiale Icterus cucullatus and jaundice parisorum, the woodpeckers Melanerpes uropygialis and Colaptes chrysoides that Beutelmeise Auriparus flaviceps and Rosefinch Carpodacus mexicanus of.
The already mentioned as pollinators woodpeckers build a few meters above their nests in the trunks. The large cacti are also birds of prey such as hawks as residences for hunting and in the absence of trees as the only opportunity to build protected nests.
The distribution area of Carnegiea gigantea is a part of too dry, the other side by frost, as it occurs at higher elevations of the Sonoran Desert, is tolerated by the plants but only to a limited extent and only in the short term. Other dangers are threatening the crops of bush fires and lightning strikes. Your tight running below the surface roots with which they can absorb even the smallest amounts of precipitation quickly, make them susceptible to wind damage.
The average age of Carnegiea gigantea in the habitat is about 85 years, with individual specimens over 200 years old can be. The most dangerous time of plants is their youth, in which they grow extremely slowly and American bush rat ( Neotoma ), bighorn sheep (Ovis canadensis) and jackrabbits (Lepus californicus ) and to be eaten. Ten-year plants are in nature only about 4 inches tall ( in cultivation to 10 cm). The highest growth rate of 10 to 15 cm per year to reach only been 2-8 m tall plants, then the annual growth rates decrease again. With a determined Taly Dawn Drezner formula the age of plants of a certain size and certain locations is quite accurately determined. Thus, for example, in the east of Saguaro National Park, growing 16 m tall plants are about 220 years old. Flowering size Carnegiea gigantea is about 40 years and 2.5 m in height, the first branches appear at the age of about 65 years in about 6 m height.
In the Red List of Threatened Species IUCN, the type is known as " Least Concern ( LC) ," ie, than not led at risk.