Pterocactus
Pterocactus tuberosus, flowers
Pterocactus is a genus in the cactus family ( Cactaceae ). It is the only genus in the tribe Pterocacteae in the subfamily Opuntioideae. Its botanical name derive from the Greek noun " πτερόν " ( " ptero " ) for " wing " and refers to the winged seeds that are typical and unique within the cactus in the genus.
Description
The zwergigen, succulent plants of the genus grow largely underground as geophytes. The tuberous roots form of one or more subterranean shoots, which are often decorated with thin neck-like constriction. These underground stems branch out just below the surface, forming short-lived aboveground shoots from. The small, globose to clavate or cylindrical drive segments are green to brown or purple in color and are up to 10 inches long and up to 2 inches in diameter. They often possess a papillate surface. The small and pfriemlichen leaf rudiments fall quickly. The few acicular, subulate or papery spines sit together with the glochids on the areoles. The terminal and individually appearing flowers are recessed into the top of the shoots. They are usually yellow or reddish and have a diameter of about 3 to 5 centimeters. The slightly gehöckerte Perikarpell is busy with tufts of small spines, the stamens are sensitive to touch.
The dry fruits are recessed navel -like at the top and tear near the top on like a lid. The winged seeds is more or less circular, light beige and papery. The aril is designed as a broad wings.
Systematics and distribution
The species of the genus are found throughout Argentina and also occur in southern Chile. The main distribution area is in the south and west of Patagonia.
The first description was published in 1887 by Karl Moritz Schumann. As type species he chose kuntzei Pterocactus. Based on morphological features they put Alexander Borissovitch Doweld 1999 as the only genus in the tribe he created Pterocacteae. The taxonomic position of the genus within the subfamily Pterocactus Opuntioideae is undisputed. Molecular genetic studies show that the genus is monophyletic.
Belong to the genus of the following types:
- Pterocactus araucanus A.Cast
- Pterocactus australis ( F.A.C.Weber ) Backeb.
- Pterocactus fischeri Britton & Rose
- Pterocactus gonjianii R.Kiesling
- Pterocactus hickenii Britton & Rose
- Pterocactus megliolii R.Kiesling
- Pterocactus reticulatus R.Kiesling
- Pterocactus tuberosus ( Pfeiff. ) Britton & Rose
- Pterocactus valentinii Speg.