Publication: Kakteen Sukk. 42: 194, figs. 1991
Description
Arrojadoa dinae var. nana is smallish arrojadoa species, probably a synonym of Arrojadoa dinae ssp. eriocaulis. It is a miniature columnar cactus about 20-30 cm high, offseting from the base. Flowers pinkish red with a yellow tip produced from a pseudocephalium (bristly zone at stem tip).
It start flowering when about 15 cm tall.
Origin and Habitat
Eastern drainage of Serra do Espinhaço in northern Minas Gerais up to the border area of Bahia, Brazil.
Altitude range: It occurs at elevations around 1000 metres above sea level.
Habitat and ecology: In the dry period Arrojadoa dinae var. nana is hidden among mosses, lichens and leaf litter. They grow lying on the soil or, occasionally, hanging.
Cultivation and Propagation
Arrojadoa dinae var. nana is not particularly difficult on own roots providing it is given a little extra heat during the winter, but this and all its relatives do best when grafted. Arrojadoas bloom on the forest floor all year-round and are accustomed to receiving lots of summer rain and winter dew, so they never dry out for long in the wild. They most definitely are not desert plants and don’t survive if treated as such. In arid climates they fare best in containers, where the roots remain moist longer.
Growth rate: It is a relatively rapidly growing and easily flowering species that will make clumps given the best conditions.
Soils: It likes very porous standard cactus mix soil and can also be grown in orchid bark, or on cork sheets or a tree branch like for epiphytes.
Repotting: Use pot with good drainage.
Watering: It should be watered generously during the growing season, keep drier in winter. Water them less than average if in bigger pots.
Fertilization: Feed with a high potassium fertilizer in summer.
Hardiness: Reputedly sensitive to frost (in his biotope the temperature never drops below 15 ° C), but less so if kept on the dry side prior to, and during, cold weather. However warmth throughout the year will increase the grower’s success (not less than 8-12°C during rest season).
Exposition: Outside bright, hot conditions or afternoon shade, inside it needs bright light, and some direct sun. Strong light encourages flowering and heavy wool and spine production.
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 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.
Propagation: The Arrojadoas are quite easy to grow from cuttings, seed or (often) graft. Seeds germinate in 7-14 days at 21-27° C in spring, remove the glass cover gradually as the plants develops and keep ventilated, no full sun for young plants! To make a cutting twist off a branch and permit it to dry out a couple of weeks, lay it on the soil and insert the stem end partially into the soil. Try to keep the cutting upright so that the roots are able to grow downward.
Bibliography
Major references and further lectures
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Machado, M., Braun, P., Taylor, N.P. & Zappi, D. 2013. Arrojadoa eriocaulis. The IUCN Red List of Threatened Species. Version 2015.1. <www.iucnredlist.org>. Downloaded on 14 June 2015.
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Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
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Nigel P. Taylor, Daniela C. Zappi “Cacti of Eastern Brazil” Royal Botanic Gardens, Kew, 2004
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Urs Eggli, Leonard E. Newton “Etymological Dictionary of Succulent Plant Names.” Birkhäuser 2004
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Kakteen und andere Sukkulenten. 24(5): 99–101, 1973
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Keith Grantham, Paul Klaassen “The plantfinder’s guide to cacti & other succulents” Timber Press, 18 May 1999
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Stuart Max Walters “European Garden Flora: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass” Cambridge University Press, 27 lug 1989
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