Publication: [Horridocactus paucicostatus var. viridis F.Ritter 1959]
Description
Eriosyce taltalensis subs. paucicostata is a very variable species for size and number of spines, colour of epidermis, number and form of ribs, etc. It comprises several questionable varieties and its taxonomic history has undergone several changes. The great variability of Eriosyce taltalensis subs. paucicostata is due to the fact that cross pollination among different forms and different species (in habitat and especially in collections) is very frequent and it can be quite difficult to determine what is the “pure type” and the cross. The form “viridis” is distinguishable for the green body (whereas the standard form generally has a blue-grey or grey-purple tinged stem), but even the “viridis” plants tend to take some purple in strong light during colder months or under stress conditions, and the differences among individuals may be remarkable. It can happen that two individuals of two different populations can look very similar and also, two plants of the same population can look very different.
Stem: Solitary, subglobose to elongate, up to 15 cm in diameter with abundant white wool on top.
Root: Conical taproot.
Ribs: Adult specimens have around 8-13 notched ribs, forming tubercles with sunken areoles.
Spines: Juvenile specimens have 1 central spine and 8 radials, but the numbers increase as they get older, and areoles can have over 20 spines on mature specimens.
Central spines: Dark brown to black, soon becoming chalky-white or greyish, up to 20 mm long.
Radial spines: 6-12, up to 1 cm long.
Flowers: From young areoles, campanulate or funnel-shaped, very pale pink, cream-white or pale yellowish with a vague green nuance. About 3 cm in diameter. Floral tube with abundant white wool and bristles. There might be over 50 flowers on a mature specimen (only mature specimens bloom).
Fruit: Reddish, elongate, opening by a basal pore.
Origin and Habitat
Eriosyce taltalensis subs. paucicostata f. viridis is endemic to Chile, where it occurs in the region of Antofagasta, between between Taltal and Antofagasta (extent of occurrence is approximately 11,000 km2).
Altitude range: It dwells at elevations between 50 and1,000 metres above sea level.
Habitat and Ecology: The species occurs in coastal hills (lomas costeras) on rocky soils. The species is frequent and overall the population is stable.
Cultivation and Propagation
Eriosyce taltalensis subs. paucicostata f. viridis is a slow growing but relatively easy to grow species, providing they are kept dry during autumn and winter and rot prone if kept in a non ventilated place.
Soils: Require a very fast mineral draining drying soil (70-80% grit and 20-30% of land soil). To prevent rottenness it is also advisable to surround its root neck by very rough sand or grit, this help a fast water drainage and an appropriate air circulation.
Watering Needs: Root prone it needs good drainage, waterings should regular in summer (do not overwater), to keep the plant compact and not become excessively elongated and unnatural in appearance. During the winter quiescent period, or when night temperatures remain below 10° C, it must be strictly kept dry since it is very sensitive to any moisture excesses.
Fertilization: During the beautiful season it’s good to enrich the soil using a fertilizer rich in potassium and phosphorous, but poor in nitrogen, because this chemical element doesn’t help the development of succulent plants, making them too soft and full of water.
Exposure: Requires strong sun exposure to develop good spinal growth (maximum brightness, sunlight accepted), but tolerate light shade. Some light shadow my be useful in the hottest summer days.
Frost Tolerance: Hardy to at least -5°C for a short period but cannot tolerate long standing freezing temperature, and for an healthy cultivation ensure a minimum temperature of 5° C. Assure a good ventilation. USDA Hardiness Zone 9b and 11.
Heat tolerance: Good heat tolerance, but in warmer climates it should be protected from excessive heat and too much sun sun in summer.
Maintenance: Repot in the spring, when its roots become cramped. Generally, it should be repotted every other year in order to provide fresh soil. After repotting, do not water for a week or more.
Propagation: Usually propagated from Seeds. (seldom produces offsets). Sow the seeds in spring in a well-aerated compost at a temperatures of 22-24°C . Stand the pots in water, moisten thoroughly and drain. Scatter and press lightly the seed onto the top of the compost. But do not cover the small seeds with compost. Secure a polythene bag around the pot or cover the container with glass or and place in a warm shaded place. If possible, germinate in a propagator. Some seedlings may appear within a week or 10 days others will take longer. At lower temperatures, germination usually takes considerably longer. Once germination has taken place, remove gradually the glass or plastic and move into a good light but not in direct sun. If the young plants are exposed to too much sun, or the compost dries out, they may stop growing and often turn red; once they stop, it is often difficult to persuade them to start growing again. Never let the pots dry out-but don’t saturate them either. A sodden compost is as harmful as a dry one. The seedling growth is rapid. But the seedling are often grafted because the plants on their own roots (especially the bigger ones) are extremely prone to root rot. In fact the best and older specimens are the grafted ones.
Bibliography
Major references and further lectures
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Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
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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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David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. “The New Cactus Lexicon” dh books, 2006
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“Succulent Plant Research” Volume 1, David Hunt, Richmond 1994, page. 117.
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Fred Kattermann “Eriosyce (Cactaceae): The Genus Revised and Amplified” David Hunt, 1994
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Hutchison, Cactus & Succulent Journal of America (Los Angeles) 27: 181-182 1955.
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Faundez, L., Guerrero, P., Saldivia, P. & Walter, H.E. 2013. Eriosyce paucicostata. In: IUCN 2013. “IUCN Red List of Threatened Species.” Version 2013.2. <www.iucnredlist.org>. Downloaded on 07 June 2014.
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