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Astrophytum myriostigma f. picta hort.

Family: CACTACEAE · Variety or form of Astrophytum myriostigma

Description

Astrophytum myriostigma (many dotted) is a spineless succulent plant, usually solitary or with very few basal branches. A transverse section of the stem reveal a perfect star shaped form (like the common star-fish) giving the plant the appearance of a bishop’s mitre (hence the common name Bishop’s cap)

Pictured form: The pictured form (Astrophytum myriostigma f. picta) has stem variegated with yellow, orange, red and violet. These pictured plants are very attractive and highly prized. They are often seen grafted on stronger columnar species, and cannot cannot be easily grown on their own roots. However some clones have enough chlorophyll in their tissues and can be grown on they own roots too, but very slow growing.

Stem: Globular to cylindric up to 30 cm tall (but occasionally up to 50 or more cm tall) and 10-20 cm in diameter, bright green variegated with yellow, orange, red and violet, covered with many minute white hairy scales that give it a characteristic silvery-grey appearance, but sometime naked. The scales are composed of very fine interwoven hairs, which, under a microscope, are very pretty object.

Roots: Fine, fibrous.

Areoles: Closed together

Spines: Wanting.

Ribs: Usually 5, sometimes 4(or 3) that increase to eight or more with age ( rarely even 10), vertical, regular, deep, prominent, very broad and acute.

Flowers: Funnelform, 4-7 cm long glossy yellow and sweet scented from the areole at the tip of the stem on mature plant. Outer perianth segments narrow, with brown scarious tips. Inner perianth segments numerous, oblong yellow with a silky shine. Scales on ovary tube scaroious, imbricated, very narrow often bristly tipped, with long wool in their axil.

Blooming season: Flowers appear intermittently throughout the warm months from April to September. Plants may take up to six years to flower.

Fruit: 2-2,5 cm in diameter, greenish to tannish-red, covered with brown, overlapping scales, with long wool in their axil.

Seeds: Dark brown, helmet-shaped, shining, with a large depressed hilum, the margins being turned in.

Origin and Habitat

Garden origin (Nursery produced cultivar)

Cultivation and Propagation

Variegated and albinous cacti are regarded as choice and difficult in cultivation, but despite that many of them are relatively easy to grow. But be aware that they cannot tolerate prolonged exposure to direct sun light (especially during the hottest summer days), so grow them in half-shade or under filtered sun. They are sometime seen as grafted plants, but many grow well on their own roots, too.

On the contrary, the albinos can survive only if grafted on a strong green base.

Use mineral well-permeable substratum with little organic matter (peat, humus). Water sparingly from March till October and keep perfectly dry in winter at temperatures from 5 to 15 degrees centigrade. (In general these plants are more tender and cannot endure freezing temperatures ) In the rest period no high atmospheric humidity!!

Propagation: Usually by seed. Plants are often grafted onto column-shaped cacti.

Bibliography

Major references and further lectures

1)James Cullen, Sabina G. Knees, H. Suzanne Cubey “The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass” Cambridge University Press, 11/Aug./2011

  1. Edward F. Anderson “Das große Kakteen-Lexikon.” Eugen Ulmer KG, Stuttgart 2005

  2. Keith Grantham, Paul Klaassen “The plantfinder’s guide to cacti & other succulents” Timber Press, 18/mag/1999

  3. Britton & Rose “The Cactaceae” 4: 273, 1923

  4. Hiroshi Hirao “Colour encyclopaedia of cacti” Japan 1979 (Japanese language and script)

  5. Willy Cullmann, Erich Götz (Dozent Dr.), Gerhard Gröner “The encyclopedia of cacti” Portland, OR: Timber Press, 1986

  6. David Hunt, Nigel Taylor “The New Cactus Lexicon” DH Books, 2006

  7. Curt Backeberg “Cactus Lexicon” Sterling Publishing Company, Incorporated, 1978

  8. Del Weniger “Cacti of the Southwest: Texas, New Mexico, Oklahoma, Arkansas, and Louisiana” University of Texas Press, 1969

  9. Del Weniger “Cacti of Texas and Neighboring States: A Field Guide” University of Texas Press, 1984