Description
Astrophytum myriostigma nudum cv. Yoroi, in Japanese speaking Yoroi kikko herikan (Armoured Kikko Hekiran) is a rare cultivar involving Astrophytum myriostigma cv. Kikko nudum and Astrophytum myriostigma cv. Fukuryu (type B) nudum. It shows both the prominent pointed tubercles along the ribs edges of “Kikko” and the irregular (more or less prominent) supplemental ribs between and on the ribs surface of “Fukuryiu”. The whole plant shows an irregular saw tooth design which is raised above the surface. This plant is also known as “Green dragoon”. The seedling grows into a cactus with a diameter of about 12 cm in diameter.
Derivation of cultivars name: “Yoroi” is the traditional Japanese armour of the samurai, the authors of the cultivars name specifically refers to the shoulders of the armour. These traditional shoulders thrown back and overlapping each other, so this “kikko” puts one in mind of a Japanese warrior (samurai) clad in armour and going off to battle, hence the name.
Similar cultivars: Compare with Astrophytum myriostigma cv. Kikko Fukuryiu an hybrid cultivar involving Astrophytum myriostigma cv. Fukuryu (type A) nudum as a parent (not type B!!)
Origin and Habitat
Japan, Garden origin (Nursery produced cultivar). Astrophytum myriostigma cv. Yoroi (Yoroi Kikko Hekiran) was born in Mr. Miura’s greenhouse. Mr. Miura is a technician who for many years worked for an agricultural machinery manufacturer. Perhaps his work required him to focus on fine detail and be persistent, but the fact is that he’s in a league of his own in terms of the passion he has for cacti. He shares with Mr Yoshinaga, his former teacher who’s been his senior for 45 years, an all-consuming passion for myriostigma, and is one of the old-timers who represent the island of Shikoku. Tetsuo Miura, born in 1942.
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
- Sumihiro Saeki “The history of Astrophytum in Japan” Cactus Nursery Saisen-en October 30, 2011
Gallery
