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Astrophytum asterias rare cactus plants

 

 Below is the detailed description of

 Astrophytum asterias

Astrophytum asterias is a species of cactus in the genus Astrophytum, and is native to small parts of Texas in the United States and Mexico. Common names include Sand Dollar Cactus, Sea Urchin Cactus, Star Cactus and Star Peyote. Wikipedia

FamilyCactaceae (Cactus Family)

Scientific nameAstrophytum asterias (Zucc.) .

 Origin is native to small parts of Texas in the United States and Mexico. 

 Conservation status: Listed in CITES appendix 1

 . Habitat destruction has been, and remains, the major cause of the decline in this species; vast areas have been converted to agricultural use and road construction.[6] In Texas, mechanical and chemical bush clearing techniques together with the introduction of invasive grasses have had devastating effects.[6]

The U.S. Fish & Wildlife Service have drafted a Recovery Plan in an attempt to secure the future of this species.[6] The Recovery Plan highlights the need to protect existing populations, carry out research into possible new populations and to develop a formal conservation agreement between the United States and Mexico.[6]

 HabitatStar cactus is native to the lower Rio Grande Valley of Texas in the United States[5][7] and the states of Nuevo León and Tamaulipas in Mexico,[2] to the east of the Sierra Madre Oriental mountain range.[4]

Previously more abundant, this species is today restricted to a single 200-acre site in Texas, where there are around 2,000 individuals,[6][8] and a few small sites in Tamaulipas.[9] Today this species is associated with thorn scrub, amongst rocky ground; it may have previously occupied richer, flat grasslands that have since been developed.[4] It has probably been extirpated from Nuevo León.[8]

 Common English NamesSand Dollar Cactus, Sea Urchin Cactus, Star Cactus and Star Peyote.

Etymology: The generic  name"Astrophytum" derives from the Greek words "aster (αστηρ)", meaning a"star" and "phyton (φυτον)", meaning"plant". ( The Genus name implies:"star plant"). 
The specific name "
asterias" derives from the Greek name “aster (αστηρ)”that means “a star” an aster type plant*,  and the Greek suffix “ias (-ιας) ”meaning “like to, comparable, similar”  The specific name implies: "star like (like an aster)"  
The shell of a sea urchin

This picture of Astroohytum asterias is from my cactus collection

 Description: Solitary geophyte cactus.

A. asterias is small, round, spineless and squat, reaching a height of 2.5–6 cm (0.98–2.4 in) and a diameter of 5–15 cm (2.0–5.9 in).[3] The disc-shaped body is divided into 7 - 10 sections, known as ribs; in the middle of each rib there are woolly areoles.[4] The body is a greenish-brown color and may appear speckled from its covering of white scales.[5] 

Stem: small, round, spineless and squat, reaching a height of 2.5–6 cm (0.98–2.4 in) and a diameter of 5–15 cm (2.0–5.9 in)

Ribs: 5(8)11, generally it has eight flat ribs, rare few or more. ( but in cultivation selected

Areolesround, cream-colored till white hairy up to 6 (3-12) mm) of diameters. The areoles are normally set in a separation up to 10 mm, but can be very close one to each other at cultivated plants.

Spines: Not any. Only seedlings show some rudimentary spines within the first weeks and months.

Roots: the underground body is fleshy, turnip-like, with fine roots.

Hairy scales: usually loose - are sprinkled over the stem in irregular patterns, sometimes arched around the areoles or on line. Cultivated plants possess sometimes very dense and big hairy scales. There are also completely flake free pure green specimens. On the picture below is the Japanese cultivar Super Kabuto with very dense scales. Picture was taken from Wikipadia

The popularity of this species among collectors and enthusiasts has ensured that a number of cultivars are available. One such cultivar is the 'Super Kabuto', a highly spotted white clone. It is shown on the picture above.

Flowers: are usually yellow with a red, orange  throat, plants start blooming when cactus rich about 3 cm diameter. 

Bloom time: from spring to summer 

Recommended Temperature Zone: 9 to 11  

Frost Tolerance: -7º C (20º F) if the soil is completely dry

Minimum Avg. Temperature: 5º C (40º F)

Watering NeedsA. asterias can take full sun in most regions, but care should be taken to protect from the intense afternoon Southwest USA heat and sun (Arizona, Nevada, California) Light to medium watering during the growing season is all that is needed. Make sure to use a well draining soil mix and that it dries out completely between watering. This specie can handle short spurts of cold temps down to 20F if the soil is kept completely dry and the ambient air is dry. If frequent frosts or humidity are also present, it may cause some orange spotting. Best to keep the plant around/above 40F and protected from frost.

Cultivation: is not too difficult in a greenhouse, although grows quite slowly. The plants need  a loose well-drained mineral soil. They need a good amount of light. Watering can be done weekly during summertime, if the weather is sunny enough, with a little fertilizer added. Kept this way, plants will show a healthy, although slow growth. They are frost hardyto -4° (-10°) C

Sand Dollar Cactus has been grown as a houseplant[10] since the 1840s,[4] like other members of its genus and despite its rarity in the wild. It is readily propagated from seed,[4] so most plants encountered in nurseries are seed grown. The popularity of this species among collectors and enthusiasts has ensured that a number of cultivars are available. One such cultivar is the 'Super Kabuto', a highly spotted white clone.

Propagation: By seeds, remembering that  seedlings dislike strong light and dry conditions  and need to be repottedfrequently. Eventually, as they become mature, they attain a maximum size of 8-10 cm (20) cm. However, old plants become senile and have a tendency to succumb to diseaseand a weak root system. At this stage, as is well known, theydie suddenly. So, after they reach 10 cm in diameter grow them slowly, and adopt a new repotting period, using intervals of every 2 - 3 years. Additionally grow them under drier conditions or with stronger sunlight. But plants are often grafted to accelerate growth as they would generally take at least a five years to reach maturity on their own, but the grafted plants are typical rather tall growing, compared with plants on their own roots that are usually more flat to the ground.

Pests: Parasitic nematodes (Xiphenema sp.)

Falcifer ground mealybag (Rhizzoecus falcifera)

Privet mite (Brevipalpus obovatus)

 Diseases:  Basal rot (Sclerotium cacticola)                                                                                  

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