Origin and Habitat: North of Carazinha, Rio Grande do Sul, Brazil

• Notocactus arechavaletae var. rubescens F.Ritter

• Parodia ottonis (Lehm.) N.P.Taylor
• Cactus ottonis Lehm.
• Echinocactus ottonis (Lehm.) Link & Otto
• Malacocarpus ottonis (Lehm.) Britton & Rose
• Notocactus ottonis (Lehm.) A.Berger
• Peronocactus ottonis (Lehm.) Doweld
• Echinocactus ottonis var. pallidior Monv. ex Lem.
• Echinocactus ottonis var. spinosior Monv. ex Lem.
• Echinocactus tenuispinus var. minor Link & Otto
• Notocactus acutus F.Ritter
• Notocactus oxycostatus f. acutus (F.Ritter) N.Gerloff
• Notocactus arechavaletae (Speg. ex Arechav.) Herter
• Echinocactus acuatus var. arechavaletae K.Schum. ex Speg.
• Echinocactus arechavaletae Speg. ex Arechav.
• Malacocarpus arechavaletae (Speg. ex Arechav.) A.Berger
• Wigginsia arechavaletae (Speg. ex Arechav.) D.M.Porter
• Notocactus arechavaletae var. alacriportanus F.Ritter
• Notocactus arechavaletae var. aureus F.Ritter
• Notocactus ottonis f. aureus (F.Ritter) N.Gerloff & Neduchal
• Notocactus arechavaletae var. buenekeri F.Ritter
• Notocactus arechavaletae var. limiticola F.Ritter
• Notocactus arechavaletae var. nanus F.Ritter
• Notocactus arechavaletae var. rubescens F.Ritter
• Notocactus grandiensis Bergner
• Notocactus maldonadensis (Herter) Herter
• Echinocactus maldonadensis Herter
• Notocactus neo-ottoianus Y.Itô
• Notocactus ottonis var. acutangularis F.Ritter
• Notocactus ottonis var. albispinus Backeb.
• Notocactus ottonis var. elegans Backeb.
• Notocactus ottonis f. elegans (Backeb. & Voll) Havlíček
• Notocactus ottonis var. globularis (F.Ritter) Bergner
• Notocactus globularis F.Ritter
• Notocactus ottonis f. globularis (F.Ritter) N.Gerloff & Neduchal
• Notocactus ottonis var. janousekianus K.Papoušek
• Notocactus ottonis var. nigrispinus H.D.Lück
• Notocactus ottonis var. paraguayensis (Haage jr.) A.Berger ex Backeb.
• Echinocactus ottonis var. paraguayensis Haage jr.
• Echinocactus ottonis f. paraguayensis (Haage jr.) Schelle
• Notocactus ottonis var. rubrispinus Prestlé
• Notocactus ottonis subvar. rubrispinus Prestlé
• Notocactus ottonis var. schuldtii Kreuz.
• Notocactus oxycostatus var. schuldtii (Kreuz.) N.Gerloff
• Notocactus ottonis var. stenogonus Backeb.
• Notocactus ottonis var. tenebrosus n.n.
• Notocactus ottonis var. tenuispinus (Link & Otto) Borg
• Echinocactus ottonis var. tenuispinus (Link & Otto) Pfeiff.
• Echinocactus ottonis f. tenuispinus (Link & Otto) Schelle
• Echinocactus tenuispinus Link & Otto
• Notocactus neo-ottoianus var. tenuispinus (Link & Otto) Y.Itô
• Notocactus tenuispinus (Link & Otto) Herter
• Notocactus ottonis var. uruguayensis (Arechav.) Frič
• Echinocactus ottonis var. uruguayus Arechav.
• Notocactus uruguayus (Arechav.) Herter
• Notocactus ottonis var. vencluianus Schütz
• Notocactus ruoffii N.Gerloff
• Notocactus minimus var. ruoffii (N.Gerloff) N.Gerloff & Neduchal
• Notocactus tenuispinus f. cristatus P.V.Heath
• Parodia amambayensis (Werderm.) Borg
• Echinocactus amambayensis Werderm.
• Parodia paraguayensis (K.Schum.) Speg.
• Parodia ottonis var. tortuosa (Link & Otto) N.P.Taylor
• Echinocactus ottonis var. tortuosus (Link & Otto) K.Schum.
• Echinocactus ottonis f. tortuosus (Link & Otto) Schelle
• Echinocactus tortuosus Link & Otto
• Notocactus neo-ottoianus var. tortuosus (Link & Otto) Y.Itô
• Notocactus ottonis var. tortuosus (Link & Otto) Borg

• Parodia ottonis subs. horstii (F.Ritter) Hofacker
• Notocactus arechavaletae var. horstii F.Ritter
• Notocactus horstii F.Ritter
• Notocactus ottonis subs. horstii (F.Ritter) Doweld
• Parodia horstii (F.Ritter) N.P.Taylor
• Peronocactus horstii (F.Ritter) Doweld
• Peronocactus ottonis subs. horstii (F.Ritter) Doweld
• Wigginsia nothohorstii (F.Ritter) Doweld
• Notocactus horstii f. muglianus K.Herm
• Notocactus horstii f. purpureiflorus (F.Ritter) K.Herm
• Notocactus horstii var. purpureiflorus F.Ritter
• Notocactus horstii f. purpureus (F.Ritter) K.Herm
• Notocactus purpureus F.Ritter
• Notocactus muegelianus T.Engel

Description: Plant at first solitary that matures and flowers at an early age. With time it form small colonies. One of the peculiarity of this species is the tendency to produce basal suckers on the lateral roots.
The "rubescens" is merely one of the several forms of the very variable Notocactus (Parodia) ottonis distinguished by its redder stems. However Parodia ottonisSN|748]]SN|748]] occurs over quite a wide area and "rubescens" is regarded as a mere ecotype with size or colour modified by more humid or arid conditions and merging into typical plants in cultivation. However redder forms occours at random elswhere.
Stem: Up to 8 cm in diameter, 4 cm tall, somewhat depressed, with white wool apically, more or less glossy green or bluish green which can take a purple colour in under stress condition or in full sun. The rich magenta colour of the stem sometime seen is due to a full sun exposure along with short water supply during cold winter month, otherwise the plant is green.
Ribs: 8-9, broad and rounded, well defined.
Areoles: Few, circular up 1-2(-3) mm wide, 10-12 mm apart.
Spines: Bristly, acicular, slightly curved and spreading.
Central spines: Up to four, brownish, reddish brown or yellowish 20-40 mm long.
Radial spines: 7-9 up to 15 mm long, clearer.
Flowers: Yellow from the uppermost areoles, one or more appearing at a time, that open only during the dayt, 5-6 cm wide, floral tube with brownish wool and bristles. Perianth segments linear-oblong, acute, stamens about half the length of the perianth, segments, style yellow, stigma lobes red.
Fruits: 0,9-12 mm in diameter, ovoid to short cylindrical, thick walled, deishent often with large number of seeds.
Seeds: Bell shaped, glossy.

Notes: Root suckers are new shoots that arise from adventitious buds developing on the lateral root system of many plants species. They are however a quite rare kind of vegetative reproduction strategy in cactus family, but occasionally occur in some cactus species when roots have been injured or felled. Notocactus arecavaletai var. rubescens is one of the few specie that produces naturally a large numbers of them and can develop into a small colony. The suckers have the potential to develop rapidly, fed by the existing root system. Often sprouting results in multiple stemmed plants.

Bibliography: Major references and further lectures
1) Tony Mace “Notocactus: a review of the genus incorporating Brasilicactus, Eriocactus and Wigginsia” Editorial Board/National Cactus & Succulent Society, 1975
2) Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
3) 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
4) David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. "The New Cactus Lexicon" dh books, 2006.

Cultivation and Propagation: It is easy to grow. It prefers a neutral to slightly acidic mineral-based potting mix with plenty of extra grit and feed during the summer. It likes a warm bright location, does great in partial shade but doesn't like full, hot blazing sun in the central summer month. Can support quite some water during the growing season but pot plants in winter are wet-sensitive and needs to be kept dry (rots easily if soil is wet and cold) tends to lose its roots in winter. Water Best if watered with rain water. Usually it is recommended to over-winter this plant in a bright and warm greenhouse with at least 8-10° C and rather dry (it tends to lose its roots and to rot if the substrate is wet and cold) but it has proved to tolerate temperatures as low as -5° C for short periods. It is susceptible to spider mites, so it should be check once in a while for it.
Propagation: Seeds, cuttings or root suckers (if available). Not too difficult to raise from seed.