''Astrophytum'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

of six species of

cacti 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 Gree ...

, native to North America. These species are sometimes referred to as living rocks, though the term is also used for other genera, particularly ''

Lithops ''Lithops'' is a genus of succulent plants in the ice plant family, Aizoaceae. Members of the genus are native to southern Africa. The name is derived from the Ancient Greek words () 'stone' and () 'face', referring to the stone-like appearanc ...

'' (

Aizoaceae The Aizoaceae, or fig-marigold family, is a large family of dicotyledonous flowering plants containing 135 genera and about 1800 species. They are commonly known as ice plants or carpet weeds. They are often called vygies in South Africa and New ...

). The generic name is derived from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

words άστρον (''astron''), meaning "star," and φυτόν (''phyton''), meaning "plant."

Description

The species of the genus ''Astrophytum'' usually grow individually with spherical to columnar green shoots and reach heights of up to 1.5 meters. The shoots are often densely covered with fine white tufts of hair, but sometimes they are completely bald. There are four to ten (rarely three) very noticeable ribs that are not divided into cusps. The large areoles stand close together, but do not merge. The spike is variable. Spines may be present or may be missing entirely. The funnel-shaped, large

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechanism ...

s are yellow or yellow with a red throat. They appear at the top of the shoots and open during the day. The pericarpel is covered with pointed scales. The cap-shaped

seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosper ...

s have a diameter of up to 2.5 millimeters with a brownish black seed coat which is almost smooth. The edge is rolled towards the sunken hilum.

Species

Synonymy

The genus has several

synonyms A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are ...

: *''Astrophyton'' Lawr., orth. var. *''Digitostigma'' Velazco & Nevárez *''Maierocactus'' E.C.Rost There are a number of species synonyms sometimes seen:

References

"''Astrophytum''"
cactiguide.com. Retrieved July 28, 2005.

"Astromaniacs"
A German / English worldwide forum for fans of ''Astrophytum''

External links

* * {{Taxonbar, from=Q286055 Cacti of North America North American desert flora Cactoideae genera