Publication: Kaktusy (Brno) 2005/2
Description
Gymnocalycium spegazzinii var. unguispinum is a depressed globular cactus distinguished from the type species for its very short spine clusters. The var. unguispinum (sometime labelled as form, subspecies or cultivars) is a rare, naturally occurring, mutant collected and selected for particular characters. Typically it has only 5 short spines less than 1 cm long, these are stout, subulate, eagle claw-shaped, typically-twisted and curved gracefully outward and downward. The name ‘unguispinus’ is not accepted by botanists that treat it as synonym (or cultivars), but it has a value for a collector because they identify plants with particular characters.
Stem: Depressed, globular, about 6 cm high, 14 cm in diameter, grayish green.
Ribs: 13, broad and low, rounded on the margin.
Areoles: Elliptic.
Origin and Habitat
Gymnocalycium spegazzinii var. unguispinum has been found in nature in the South of Puerta Tastil, Salta, Argentina.
Field number: SL 44b.
Altitude range: Around 3000 metres above sea level.
Cultivation and Propagation
Gymnocalycium spegazzinii is a summer grower species that is easy to cultivate.
Growth rate: It is a slow growing and easily flowering species.
Soils: It likes very porous standard cactus mix soil. Prefer a low pH compost, avoid substrata rich in limestone; otherwise growth will stop altogether.
Repotting: This plant needs plenty of space for its roots, repotting should be done every other year or when the it has outgrown its pot. Use pot with good drainage.
Watering: Needs moderate to copious waterings in summer, but do not overwater (Rot prone), keep dry in winter at a minimum temperature of 0°C.
Fertilization: Feed with a high potassium fertilizer in summer.
Hardiness: Reputedly resistant to frost if kept on the dry side prior to, and during, cold weather (hardy to -12 C ° C, or less for short periods), but for safe cultivation it is best to avoid freezing temperatures.
Exposition: The plant tolerates extremely bright situations but enjoys filtered sunlight or afternoon shade, inside it needs bright light, and some direct sun. Tends to bronze in strong light, which encourages flowering and heavy spine production, but is likely to suffer from sun scorch or stunted growth if over exposed to direct sunlight during the hottest part of the day in summer.
Uses: It is an excellent plant for container growing. It always looks good and stays small. It look fine in a cold greenhouse and frame or outdoor in a rockery.
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: This species is particularly easy and accommodating, seldom suffer of cryptogamic diseases. Rot it is only a minor problem with gymnocalyciums if the plants are watered and “aired” correctly. If they are not, fungicides won’t help all that much.
Propagation: Division, direct sow after last frost. Seeds germinate in 7-14 days at 21-27° C in spring, remove gradually the glass cover as soon the plants will be well rooted (ca 1-2 weeks) 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 somewhat upright so that the roots are able to grow downward.
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