Astrophytum asterias (Zucc.) Lem.

 

Origin and Habitat: It was once found throughout Texas and Mexico in an area of occupancy of less than 2,000 km² at the Mexico-USA border to the east of the Sierra Madre Oriental mountain in the states of Tamaulipas (Gonzales, El Hundido, Estancion Calles, Fortin Agrero, Llera, Ejido 21. Marzo, Rancho San Antonio, South of San Carlos and south of Cd. Victoria), Nuevo Leon (Lucio Blanco) and the lower Rio Grande Valley, of Texas in the United States (Starr and Hidalgo County).
Altitude: 50-200 metres above sea-level.
Habitat: It grow on hills, hollows and along the sides of dry river beds, on gravelly alluvial loams and saline or calcareous clays in thorn shrub vegetation and grasslands in warm-temperate, subtropical steppe climate (semi-desert). Astrophytum asteriasSN|1464]]SN|1464]] is mainly found in the shade of other plants or rock in the grass up to the edge of the bushes almost completely buried underground, often covered by sand. It is very cryptic. Its colours matches that of the surrounding soil and is difficult to spot if not in flower. Associates succulents include Opuntia leptocaulisSN|10936]]SN|10936]], Mammillaria heyderiSN|20805]]SN|20805]], Thelocactus schwarziiSN|15806]]SN|15806]], Echinocereus reichenbachiiSN|7575]]SN|7575]] var. fitchii, Homalocephala texensisSN|2230]]SN|2230]], Pilosocereus palmeriSN|6732]]SN|6732]], Coryphantha macromeris var. runyoniiSN|10029]]SN|10029]] and Stenocereus pruinosusSN|7951]]SN|7951]]. Precipitation less than 500 mm per annum. Much of its original habitat has been destroyed by habitat destruction, agricultur, collecting and foraging by cottontail-rabbits in Texas and in Tamaulipas. Once fairly widely distributed in south Texas, the species is now known from only one locality near Rio Grande City. Several localities are known in Mexico, both north and south of Ciudad Victoria. The species may also have occurred in the State of Nuevo León and is hence Regionally Extinct there. The total population numbers more than 5,000 plants from known localities in both countries.

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Synonyms:

• Astrophytum asterias (Zucc.) Lem.

Common Names include:
ENGLISH: Sand Dollar Cactus, Sea Urchin Cactus, Star Cactus, Star Peyote
CHINESE (中文): 星葉球
DUTCH (Nederlands): Zeeëgelcactus
FRENCH (Français): Cactus oursin
GERMAN (Deutsch): Seeigelkaktus
HUNGARIAN (Magyar): Csillagkaktusz
JAPANESE (日本語): 兜丸
LITHUANIAN (Lietuvių): Tikrasis žvaigždinas
RUSSIAN (Русский): Астрофитум звёздчатый, Астрофитум астериас
SLOVAK (Slovenčina): Astrofyt ježovkový
SPANISH (Español): Biznaga algodoncillo de estrella, Cacto estrella
SWEDISH (Svenska): Sjöstjärnekaktus, Stjärnkaktus

 

Description: Astrophytum asteriasSN|1464]]SN|1464]] (a.k.a. Sea-Urchin Cactus or Sand Dollar) is an extremely flat barrel cactus with unique and remarkably beautiful form and no typical covering of spines, but with tiny speckled tuft of hairs less than pinhead-sized. It produces large yellow flowers with orange throats often larger than the plant itself. The common name comes from resemblance to sea urchin without spines.
Habit: It is a solitary (unless damaged) perennial stem succulent growing deep seated just flat to the ground surface. Only in cultivation plants may have a spherical till columnar shape.
Roots: The underground body is fleshy, turnip-like, with fine diffuse roots.

Stem: Non-branched, much depressed, disc-shaped to low dome-shaped, grey-green to dull green (unless stressed), mature plants 2-7 cm tall, 5-16 cm broad, dotted with numerous minuscule tufts of bright white wool (hairy scales). These hairy scales are usually loose, 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. The short white wool on surface, said to substitute for lack of shade from spines. There are also completely flake free pure green specimens.
Ribs: The stem is typically divided by very narrow but distinct vertical grooves into 8 broad ribs. The ribs are very low, almost flat on top, forming triangular sections with no cross-grooves. The normal rib number eight is very stable in wild specimens, independent of the age of the plant, but in cultivation selected cultivars and hybrids can have from 4 to 13 ribs.
Areoles: Round, prominent, 3-12 mm in diameters, forming a line up to the centre of each rib, felted to hairy, white, creamy, dirty-yellow till straw-coloured, then grey. Normally 3 to 10 mm apart, but sometime very close one to each other in cultivated plants.
Spines: Not any. Only seedlings show some rudimentary spines within the first weeks and months.
Flowers: Apical, diurnal, radial, 3-5 cm long, 5-7(-9) cm in diameter opening widely, yellow with orange/red throats. Ovary and tube very short, densely covered with thin, bristle-like, black tipped scales and with cobwebby wool in axils. Outer tepals short, narrow, pointed, greenish, covered with short fuzz on outer surfaces; inner tepals long, slightly spatulate, from narrow orange-red bases; upper parts clear yellow, edges entire, tips entire and slightly pointed to erose and irregular. Filaments orange at bases, yellow above, anthers and pollen yellow. Style yellowish with 10-12 yellowish-green stigma lobes.
Blooming season: In habitat the flowering period is spring and each flower lasts for one or two days only, but the plant may flower at any time during the warmer months of the year if adequate water is provided.
Fruits: Oval to round, about 1,5-2 cm long, green, pinkish or greyish-red densely covered with spines and dull-white wool, becoming dry and finally breaking off at or near base (not opening above the base).
Seeds: Black or dark brown, glossy, bowl to helmet shaped about 2 mm long, 3 mm broad.
Similar species: Astrophytum asteriasSN|1464]]SN|1464]] is sometimes confused with peyote (Lophophora williamsiiSN|1117]]SN|1117]]). Both species are spine-less, and peyote often has 8 ribs. However, peyote is bluish-green but has irregularly shaped ribs and lacks the tiny whitish scales.
Remarks: The stem is said to be suffused with chemical compounds distasteful to herbivores.

Astrophytum asterias (llifle.com)