''Astrophytum asterias'' is a species of

cactus A cactus (, or less commonly, cactus) is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1750 known species of the order Caryophyllales. The word ''cactus'' derives, through Latin, from the Ancient Greek ...

in the genus ''

Astrophytum ''Astrophytum'' is a genus of six species of cacti, native to North America. These species are sometimes referred to as living rocks, though the term is also used for other genera, particularly ''Lithops'' (Aizoaceae). The generic name is der ...

'', and is native to small parts of

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

and

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. Common names include sand dollar cactus, sea urchin cactus, star cactus and star peyote.

Description

''A. asterias'' (also known as the Star Cactus) is small, round, spineless and squat, reaching a height of and a diameter of . The disc-shaped body is divided into 7–10 sections, known as ribs; in the middle of each rib there are woolly areoles.Anderson, E.F., Arias Montes, S. & Taylor, N.P. (1994) Threatened Cacti of Mexico. Royal Botanic Gardens, Kew. - via

ARKive ARKive was a global initiative with the mission of "promoting the conservation of the world's threatened species, through the power of wildlife imagery", which it did by locating and gathering films, photographs and audio recordings of the worl ...

The body is a greenish-brown colour and may appear speckled from its covering of white scales (

trichomes Trichomes (); ) are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a plant ...

). The flowers of this cactus are yellow with red bases and the outer parts are very woolly. Green to pink oval fruits are produced; the outside coat is covered with woolly hairs.

Biology

Reproduction takes place via sexual outcrossing through cross-pollination; star cacti reach sexual maturity after a few years, when they have attained in diameter. Flowers are produced from March to June (the summer season in its native habitat) and fruiting occurs from April to June. The primary pollinators of ''A. asterias'' are medium to large size bees with one species, Diadasia rinconis being the most effective. The plant also bears a superficially close resemblance to the unrelated '' Euphorbia obesa'', which actually is not a

; simply put, all cactus are a ''succulent'', and by their very nature they, themselves, are ''succulent'' (I.e., storing water for future droughts). But not every ''succulent'' is going to be a cactus. Another key difference between cacti and ''Euphorbiaceae'' is origin and wild distribution. Cacti, including Astrophytum, are predominately found on the American continents, with a great variety in South America and Mexico. Though they are diverse, and widespread globally, the majority of ''

Euphorbia ''Euphorbia'' is a very large and diverse genus of flowering plants, commonly called spurge, in the family Euphorbiaceae. "Euphorbia" is sometimes used in ordinary English to collectively refer to all members of Euphorbiaceae (in deference to t ...

'' succulents are found in Africa, the Middle East, and India. Furthermore, all members of ''

Euphorbiaceae Euphorbiaceae, the spurge family, is a large family of flowering plants. In English, they are also commonly called euphorbias, which is also the name of a genus in the family. Most spurges, such as ''Euphorbia paralias'', are herbs, but some, e ...

'' produce a potentially irritating, caustic latex sap that can cause blindness if eye contact is made. Cacti, by comparison, are mostly non-toxic, with many well-known species producing edible fruits (such as prickly pear,

dragonfruit A pitaya () or pitahaya () is the fruit of several different cactus species indigenous (ecology), indigenous to the Americas. Pitaya usually refers to fruit of the genus ''Stenocereus'', while pitahaya or dragon fruit refers to fruit of the ge ...

, or

epiphyllum ''Epiphyllum'' (; "upon the leaf" in Greek) is a genus of epiphytic plants in the cactus family (Cactaceae), native to Central America and South America. Common names for these species include climbing cacti, orchid cacti and leaf cacti, though ...

), eaten by humans and animals alike. One of the very few commercially viable Euphorbias, for humans, would be the

poinsettia The poinsettia ( or ) (''Euphorbia pulcherrima'') is a commercially important flowering plant species of the diverse spurge family Euphorbiaceae. Indigenous to Mexico and Central America, the poinsettia was first described by Europeans in 1834 ...

s that are sold each year in November and December.

Distribution and habitat

Star cactus is native to the lower

Rio Grande Valley The Lower Rio Grande Valley ( es, Valle del Río Grande), commonly known as the Rio Grande Valley or locally as the Valley or RGV, is a region spanning the border of Texas and Mexico located in a floodplain of the Rio Grande near its mouth. The ...

in the

IUCN Red List
(February 2003) and the states of

Nuevo León Nuevo León () is a state in the northeast region of Mexico. The state was named after the New Kingdom of León, an administrative territory from the Viceroyalty of New Spain, itself was named after the historic Spanish Kingdom of León. With a ...

and

Tamaulipas Tamaulipas (), officially the Free and Sovereign State of Tamaulipas ( es, Estado Libre y Soberano de Tamaulipas), is a state in the northeast region of Mexico; one of the 31 states which, along with Mexico City, comprise the 32 Federal Entiti ...

, to the east of the Sierra Madre Oriental mountain range. Previously more abundant, this species is today restricted to a small portion of Starr County, Texas, and a few localized sites in Tamaulipas. Today this species is associated with thorn scrub, amongst rocky ground; it may have previously occupied richer, flat grasslands that have since been developed. It has probably been

extirpated Local extinction, also known as extirpation, refers to a species (or other taxon) of plant or animal that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinct ...

from

Cultivation

Sand Dollar Cactus has been grown as a

houseplant A houseplant, sometimes known as a pot plant, potted plant, or an indoor plant, is an ornamental plant that is grown indoors. As such, they are found in places like residences and offices, mainly for decorative purposes. Common houseplants are us ...

since the 1840s, like other members of its genus and despite its rarity in the wild. It is readily propagated from seed, so most plants encountered in nurseries are seed grown. The popularity of this species among collectors and enthusiasts has ensured that a number of

cultivar A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture, ...

s are available. One such cultivar is the 'Super Kabuto', a clonally propagated variety whose large trichomes congregate into dense spots, arranged in a striking pattern.

Conservation

As with certain other slowly maturing cacti, ''A. asterias'' is listed as

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...

by the

United States Fish and Wildlife Service The United States Fish and Wildlife Service (USFWS or FWS) is an agency within the United States Department of the Interior dedicated to the management of fish, wildlife, and natural habitats. The mission of the agency is "working with othe ...

, vulnerable on the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biologi ...

, and critically imperiled by

The Nature Conservancy The Nature Conservancy (TNC) is a global environmental organization headquartered in Arlington, Virginia. it works via affiliates or branches in 79 countries and territories, as well as across every state in the US. Founded in 1951, The Natu ...

.''Astrophytum asterias''.
The Nature Conservancy. It is listed on Appendix I of the

Convention on International Trade in Endangered Species of Wild Fauna and Flora CITES (shorter name for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of interna ...

(CITES),CITES (February, 2003) www.cites.org - via

meaning that commercial international trade in wild-collected specimens is prohibited. Despite this protection, illegal collection continues to threaten the future of this species. and its decline in the wild has been largely attributed to over-collection and poaching. It is sometimes accidentally harvested due to its similarity to the closely related and coexisting

peyote The peyote (; ''Lophophora williamsii'' ) is a small, spineless cactus which contains psychoactive alkaloids, particularly mescaline. ''Peyote'' is a Spanish word derived from the Nahuatl (), meaning "caterpillar cocoon", from a root , "to gl ...

(''Lophophora williamsii''). Other contributing factors are thought to be urban development and herbicides. Habitat destruction has been, and remains, the major cause of the decline in this species; vast areas have been converted to

agricultural Agriculture or farming is the practice of cultivating Plant, plants and livestock. Agriculture was the key development in the rise of Sedentism, sedentary human civilization, whereby farming of Domestication, domesticated species created food ...

use and road construction.Star Cactus Draft Recovery Plan (February, 2003) https://web.archive.org/web/20030419193014/http://ifw2es.fws.gov/Documents/R2ES/DRAFT_FR_Star_Cactus_Recovery_Plan_10-17-02.pdf - via

In Texas, mechanical and chemical bush clearing techniques together with the introduction of invasive grasses have had devastating effects. The

have drafted a Recovery Plan in an attempt to secure the future of this species. 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.

References

asterias ''Asterias'' is a genus of the Asteriidae family of sea stars. It includes several of the best-known species of sea stars, including the (Atlantic) common starfish, ''Asterias rubens'', and the northern Pacific seastar, ''Asterias amurensis''. T ...