Publication: Cactaceae (Backeberg) 5: 2656. 1961
Description
Astrophytum myriostigma var. nudum (nude form also known as “Hekiran” in Japanese speech) is very similar to the other myriostigma, it only deviate from the well-known typical form for lacking or mostly lacking white flecks, giving a bright green, blue-green, gray-green or mauve-green color overall depending on clones.
It is by some considered an extreme form of the subspecies potosinus.
Stem: Spherical to shortly columnar with age. The stems is smooth and can be over 120 cm tall and 5-10 cm in diameter and are shaped like a bishop’s headpiece or a star.
Spines: None.
Ribs: The number of ribs vary from 3 to 8 (usually 5).
Flowers: 5 cm in length, pale-yellow, silk-shining unlike the white-spotted plant, occasionally with an orange gloom.
Blooming season: Spring or early summer, They take up to 6 years to bloom.
Fruits: Dry, dehisces towards the apex forming about 5 star shaped lobes. With few seeds.
Origin and Habitat
Garden origin (Nursery produced cultivar)
Cultivation and Propagation
Astrophytum myriostigma is a summer grower species relatively easy to grow. It is sometime seen as a grafted plant but grows very well on its own roots too.
Growth rate: It is a slow growing and easily flowering species.
Soil: Use mineral well permeable substratum with little organic matter (peat, humus), plants may become too elongated if compost is too rich.
Repotting: Re-pot every 2 years. Use pot with good drainage.
Fertilization: It grows much faster with a low nitrogen content fertilizer in spring and summer. Potassium helps maintaining the plants compact and healthy.
Watering: Requires careful watering to keep plant compact. Water sparingly from March till October, the thin, fibrous roots suffer if there is humidity, therefore the plant should be watered only when the surrounding terrain is dry. Keep dry as soon as the temperature starts dropping in October and keep it perfectly dry in winter at temperatures from 5 to 15 degrees centigrade.
Hardiness: They need to be kept in a cool place during winter rest and are somewhat resistant to frost if kept on the dry side prior to, and during, cold weather (due to the altitude they are hardy to -5 C ° C, or less for short periods). Although it is one of the easier Astrophytum to grow, it tends to rot in winter during the resting phase, if kept wet. In the rest period no high atmospheric humidity!!
Sun Exposure: Light shade to full sun, its colour tends to richer and darker when grown in light shade.
Uses: It is an excellent plant for container growing. It always looks good and stays small.
Pests & diseases: It may be attractive to a variety of insects, but plants in good condition should be nearly pest-free, particularly if they are grown in a mineral potting-mix, with good exposure and ventilation. Nonetheless, there are several pests to watch for:
- Red spiders: Red spiders may be effectively rubbed up by watering the infested plants from above.
- Mealy bugs: Mealy bugs occasionally develop aerial into the new growth among the wool with disfiguring results, but the worst types develop underground on the roots and are invisible except by their effects.
- Scales: Scales are rarely a problem.
- Rot: Rot is only a minor problem with cacti if the plants are watered and “aired” correctly. If they are not, fungicides won’t help all that much. To prevent rottenness it is also advisable to surround its root neck by very rough sand or grit, this help a fast water drainage.
Propagation: Almost exclusively by seed. Plants are sometimes grafted onto column-shaped cacti. Cutting scions from a flourishing plant is almost a crime because the scions do not root easily.
Remarks: This quite variable plant has been widely grown for years and is now available in several cultivated variety and several breeds do exist. The famous “Onzuka” is only one of these and though maybe the most beautiful, but a lot of other forms are represented in many collections.
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
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Edward F. Anderson “Das große Kakteen-Lexikon.” Eugen Ulmer KG, Stuttgart 2005
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Keith Grantham, Paul Klaassen “The plantfinder’s guide to cacti & other succulents” Timber Press, 18/mag/1999
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Britton & Rose “The Cactaceae” 4: 273, 1923
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Hiroshi Hirao “Colour encyclopaedia of cacti” Japan 1979 (Japanese language and script)
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Willy Cullmann, Erich Götz (Dozent Dr.), Gerhard Gröner “The encyclopedia of cacti” Portland, OR: Timber Press, 1986
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David Hunt, Nigel Taylor “The New Cactus Lexicon” DH Books, 2006
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Curt Backeberg “Cactus Lexicon” Sterling Publishing Company, Incorporated, 1978
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Del Weniger “Cacti of the Southwest: Texas, New Mexico, Oklahoma, Arkansas, and Louisiana” University of Texas Press, 1969
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Del Weniger “Cacti of Texas and Neighboring States: A Field Guide” University of Texas Press, 1984
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Fitz Maurice, B, Sotomayor, M., Fitz Maurice, W.A., Hernández, H.M. & Smith, M. 2013. Astrophytum myriostigma. In: IUCN 2013. “IUCN Red List of Threatened Species.” Version 2013.2. <www.iucnredlist.org>. Downloaded on 23 February 2014.
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