Habitat: Southern and Western Argentina.
Cultivation: Easy. Plenty of light, a well-draining soil, mild temperatures will do well.
Curiosity: The name “Pterocactus” come from the Greek word pteron, “wing”, referring to the saucer-shaped seed of these plants.
Pterocactus is a genus in the family Cactaceae that includes 9 species of cacti with tuberous roots, native to Southern and Western Argentina. The tribe Pterocacteae owes its name to this genus, and includes only the former.
Pterocactus inhabit a wide range of altitudes: from 0 to 2500 meters above the sea level! Its preferred habitat are the shrublands and the kind of soil in which it thrives is usually salty and sandy: it also grow among dunes, almost completely buried in the sand. Pterocactus are endemic of Argentina and many of the 9 species are listed in some CITES appendixes. The CITES ( Convention on International Trade in Endangered Species of wild Flora and Fauna) is an international agreement between the Governments of different countries. Its aim is to ensure that the international trade in wild animals and plants does not threaten their survival.
Some species, such as P. tuberosus, have a really efficient reproductive system: they loose their shoots in Autumn and Winter. The sprouts are led by strong winds and give birth to new plants during the following vegetative season.
Pterocactus are geophytes which go through the winter thanks to their tuberous roots. A geophyte plant, in fact, in botany, is a plant which owes its perennial habit to some kind of subterraneus organs: tubers, rhizomes, or bulbs.
They usually have fragile, slender stems, bluish or brownish-purple or dark green. They reach a maximum length of 40 centimeters and a maximum diameter of 2 centimeters and so they break off easily (this is essential to the success of their reproductive strategy). In some species however, such as in P. fischeri, the stems can be more thick and short, maintaining, however, a cylindrical form overall. In other species instead, such as P. araucanus, the stems are grey and irregularly shaped, with conic stems along with crested ones or nipple-shaped others, colored in an unusual greish-brown, very mimetic. The entire plant, in some species, may take on a candelabriform aspect, with an erect main stem on the top of which a few shorter, radially arranged stems sprout. Usually, however, it has the aspect of a cluster of stems spruting from the tuberous roots.
The areoles may be more or less prominent and white depending on the species. In some of them they’re woolly and give birth to numerous, radially-arranged, short, white, inconspicuous spines, while in other ones they lie at the top of tubercles and are really small, almost spineless.
Roots are tuberous and usually deeply set in the ground. The tubers are brownish, very thick and grow huddled together in a globose mass.
The flowers are solitary and sprout at the top of the stems. They are of course larger than the stems and are really cute, with their numerous, pinkish-white, pale or amber-yellow or either brown and red petals and the yellow central part, filled with a crowd of 5 millimeters long stamens and a central, purplish-pink or red, prominent stigma. The stamens and the stigma are the feminine and the masculine part in an hermaphrodite flower.
The fruit is uaually rdy and provided with wings.
VARIETY AND TYPES
The genus Pterocactus includes 9 species of cacti. Here below they are:
- P. araucanus
- P. australis
- P. decipiens
- P. fischeri
- P. gonjianii
- P. hickenii
- P. kurtzei
- P. pumilus
- P. reticulatus
- P. skotssbergii
- P. tuberosus
- P. valentini
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TIPS FOR GROWING
Pterocactus is not so difficult to cultivate. Here below are our advices:
- Put your Pterocactus in bright and rather airy places.
- It prefers rather mild temperatures, however it still survives even at temperatures close to freezing if the soil is dry.
- Water moderately from March to October, only when the soil is completely dry, avoiding stagnation of water. Suspend almost completely in winter.
- A well-draining and porous soil is an optimal solution, even better if further enriched with 50% or more of inert materials such as pumice or lapilli.
- They do not need frequent fertilization, it is sufficient to dilute the fertilizer with watering once a year.
- Repotting necessities vary according on the species: once a year, anyway, is the optimal frequency.
The easiest propagation method is to take off their apical sprouts and replanting them: they will put root during the following vegetative season. Sowing is also possible.