Parodia ottonis subsp. horstii (F.Ritter) Hofacker
Notocactus arechavaletae var. horstii, Notocactus horstii, Notocactus ottonis subsp. horstii, Parodia horstii, Peronocactus horstii, Peronocactus ottonis subsp. horstii, Wigginsia nothohorstii
Parodia ottonis subsp. horstii is a solitary or slowly clustering cactus with flattened or spherical stems that have 6 to 16 ribs. The stems are green with a crown covered in spiny white wool, up to 1 foot (30 cm) tall and up to 6 inches (15 cm) in diameter. Flowers are yellowish-orange, pink or violet-purple, up to 1.4 inches (3.5 cm) in diameter, and appear in early spring.
USDA hardiness zones 9a to 11b: from 20 °F (−6.7 °C) to 50 °F (+10 °C).
If you can grow cacti and succulents successfully, you can likely grow the popular Parodia without too much trouble. It is key to remember, however, that Parodias don't like direct sunlight and are accustomed to more even water than many other cacti species. The cactus mustn't be exposed to prolonged dampness and sitting water. Never let your cactus sit in a dish of water. To encourage better flowering, allow the plants to enjoy a cooling period in the winter and dramatically cut back watering. Unlike other cacti species, however, you don't need to stop watering entirely. Lastly, make sure to fertilize during the growing season for the best results.
Repot as needed, preferably during the warm season. To repot Parodia, make sure the soil is dry before repotting, then gently remove the pot. Knock away the old soil from the roots, making sure to remove any rotted or dead roots in the process. Treat any cuts with a fungicide. Place the plant in its new pot and backfill with potting soil, spreading the roots out as you repot.
Learn more at How to Grow and Care for Parodia.
Parodia ottonis subsp. horstii is native to Brazil (Rio Grande do Sul).
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Origin and Habitat: Parodia ottonis is widespread in South America in South Brazil, Uruguay, North-east Argentina and South Paraguay.
Habitat: Subtropical grasslands. And also in this area are several species of Frailea.
Description: Parodia ottonis, better known as Notocactus ottonis, is a common attractive dwarf clumping cactus and particularly is fun as it matures and flowers at an early age. This is one of the most variable species in the genus and has lots of unnecessary synonyms and comprises a multitude of different regional forms as well as various cryptic allied species including the Parodia linkii, Parodia oxycostata, Parodia carambeiensis amd Parodia muricata. But where each form is linked to others by populations of plants with intermediate characteristics. This species is in cultivation with many cultivated and propagated forms. Generations of cactophiles have had this plant as one of their first acquisitions and few can have been disappointed by its easy cultivation and free-flowering habit.
Habit: Simple at first later usually clustering, the plants may form large clumps developing offsets on stolons which may emerge up to 20 cm away from the parent plant,
Stems: More or less spherical, tapered at base, eventually cylindrical with a flattened top, 2-15 cm in diameter (mostly less than 10 cm), light. Deep-green, bluish green, and can get deep purplish to maroon during winter dormancy, though this colour can be retained if grown in sufficient light. However the new growth is green but will soon darken to match the older epidermis.
Ribs: 6-12, rarely up to15, well defined. rounded or acute.
Spines: Slender hair-like, straight, curved or twisted, relatively sparse that does not hide the epidermis.
Central spines: 1-6, sometimes difficult to distinguish from radials, yellowish, pale to dark brown, light rose, reddish brown or black, 8-40 mm long tending to point downward.
Radial spines: 4-15 spreading radially, with a starlike appearance, whitish, yellow, pale rose or brown. 5-30 mm long.
Flowers: 3,5-6 cm in diameter, few often closely packed apically, bright satiny yellow in one rare variant orange-red, pericarpels and tube with dense white to brownish wool and bristles. Stigma-lobes usually red or purplish, rarely orange or yellow.
Fruit: Ovoid to short oblong. 9-12 mm in diameter green, not elongating at maturity, thin to thick-walled. dehiscent lengthwise to expose the seeds and white pulp.
Seeds: 15-100 per fruit. Bell-shaped glossy black, 1,2-1,4 long and 11,7-1,2 mm broad strongly tuberculate.
Subspecies, varieties, forms and cultivars of plants belonging to the Parodia ottonis group
Bibliography: Major references and further lectures
1) Krainz, Hans “Die Kakteen” 1957-1975
2) Friedrich Ritter “Kakteen in Sűdamerika: Ergebnisse meiner 20jährigen Feldforschungen” Friedrich Ritter Selbstverlag, 1979
3) E Haustein “Der Kosmos Kakteenfuehrer (the Kosmos Cactus Guide)” Balogh Scientific Books 01 December 1998
4) Mariella Pizzetti, Giuseppe Mazza “Piante grasse: le cactacee” A. Mondadori, 1985
5) Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
6) 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
7) David R Hunt Nigel P Taylor Graham Charles International Cactaceae Systematics Group. "The New Cactus Lexicon" dh books, 2006
8) Urs Eggli, Leonard E. Newton: “Etymological Dictionary of Succulent Plant Names” Springer, Berlin/Heidelberg 2010
9) 5) N. L. Britton, J. N. Rose: “The Cactaceae. Descriptions and Illustrations of Plants of the Cactus Family.” Volume III, The Carnegie Institution of Washington, Washington 1922
10) David Squire “Complete Indoor Plants” New Holland, 28/May/2007
11) Tony Mace “Notocactus: a review of the genus incorporating Brasilicactus, Eriocactus and Wigginsia” Editorial Board/National Cactus & Succulent Society, 1975
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Cultivation and Propagation: Parodia ottonis is a summer grower species easy to grow and to bloom. It makes a very suitable indoor plants for any luminous windowsills.
Growth rate: It is a moderately fast 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.
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 ( they are hardy to -5 C ° C, for short periods). Although it is one of the easier Parodia 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: Requires full sun in winter and some protection in summer, 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. Cutting scions from a flourishing plant may also been used to propagate this plant.
|Family:||Cactaceae (kak-TAY-see-ee) (Info)|
|Genus:||Parodia (par-ROH-dee-uh) (Info)|
|Species:||ottonis (o-TOE-nis) (Info)|
|Synonym:||Parodia ottonis subsp. ottonis|
Drought-tolerant suitable for xeriscaping
Average Water Needs Water regularly do not overwater
USDA Zone 9a: to -6.6 °C (20 °F)
USDA Zone 9b: to -3.8 °C (25 °F)
USDA Zone 10a: to -1.1 °C (30 °F)
USDA Zone 10b: to 1.7 °C (35 °F)
USDA Zone 11: above 4.5 °C (40 °F)
Plant has spines or sharp edges use extreme caution when handling
Allow cut surface to callous over before planting
From seed germinate in vitro in gelatin, agar or other medium
Allow seedheads to dry on plants remove and collect seeds
This plant is said to grow outdoors in the following regions:
On Jul 5, 2006, palmbob from Acton, CA (Zone 8b) wrote:
This is a variable species from several South American countries. This supspecies tends to stay globose and sucker. The other, horstii (all others listed are superflous names), tends to grow taller and is only found in one area of southern Brazil. Flowers are bright yellow in summer, and skin of this cactus can get deep red to maroon in summer. Normally it is a dark green.
On Oct 7, 2005, Xenomorf from Phoenix, AZ (Zone 9b) wrote:
More synonyms are: Notocactus acutus, Notocactus ruoffii, Notocactus uruguayus, Notocactus grandiensis, Notocactus ottonis var. uruguayensis, Notocactus neo-ottoianus, Echinocactus ottonis var. uruguayus, Echinocactus amambayensis, Notocactus arechavaletai, Malacocarpus arechavaletae, Echinocactus arechavaletae, Notocactus arechavaletae, Echinocactus acuatus var. arechavaletai, Notocactus ottonis var. janousekianus, Notocactus ottonis var. paraguayensis, Parodia paraguayensis, Notocactus tenuispinus, Echinocactus tenuispinus & Echinocactus ottonis var. tenuispinus.
The plant at first grows individually and later forms groups. The light to dark green or blue-green spherical shoots are often tapered towards the base. They reach diameters of 3 to 15 centimeters. The six to 16 distinct ribs are rounded or sharp-edged. There are usually only a few areoles on each rib . The bristle-like thorns that spring from them are straight, curved or twisted. The one to four central spines are brownish, reddish brown or yellowish and have a length of 0.8 to 4 centimeters. The four to 15 spines are whitish to yellowish or brownish and 0.5 to 3 centimeters long. 
The usually yellow flowers, rarely orange-red or red, reach lengths of 5 to 6 centimeters and would appear in late summer. Its flower tube is covered with brownish wool and bristles. The scars are dark red. The thick-walled egg-shaped to short cylindrical fruits tear open. They have diameters from 0.9 to 1.3 centimeters. The fruits contain, often very numerous, bell-shaped, glossy black seeds, which are strongly humped. 
Parodia ottonis is common in southern Brazil, southern Paraguay, Uruguay, and northeastern Argentina. 
The first description as Cactus ottonis by Johann Georg Christian Lehmann was published in 1827. Nigel Paul Taylor presented the type 1987 in the genus Parodia . Other nomenclatural synonyms are Echinocactus ottonis (Lehm.) Link & Otto (1830), Malacocarpus ottonis (Lehm.) Britton & Rose (1922), Notocactus ottonis (Lehm.) A.Berger ( 1929) and Peronocactus ottonis (Lehm.) 
The following subspecies are distinguished: