Origin and Habitat: Northern Argentina, where the species occurs in three areas: Sierra Lihuel - Calel, Sierra de Tandil, and Sierra de la Ventana and (maybe) Uruguay (Paso del Cerro)
Habitat and ecology: this species grows in the Pampa grasslands together with Gymnocalycium parvulumSN|11474]]SN|16395]], Gymnocalycium gibbosumSN|8057]]SN|8057]], Gymnocalycium bicolorSN|16395]]SN|11474]], Lobivia aureaSN|10646]]SN|10646]], Frailea astrerioides, TrichoSN'>7680' alt='6944'>Cereus candicans#SN#7679'>Tricho[[Cereus candicansSN' style='border:none;'>, CylindrSN'>28226' alt='32053'>Opuntia tunicata#SN#28228'>Cylindr[[Opuntia tunicataSN' style='border:none;'>SN|28226]], Cereus aethiopsSN|7679]]SN|6944]], Parodia submammulosaSN|20039]]SN|20039]], Opuntia pampeanaSN|32054]]SN|32054]], Opuntia sulphureaSN|28228]]SN|32053]], Notocactus submammulosusSN|20042]]SN|20042]] and the epiphyte or lithophyte bromeliad Tillandsia gilliessi, Tillandsia bryoides and Tillandsia myosura.

• Wigginsia sessiliflora (Hook.) D.M.Porter
• Echinocactus sessiliflorus Hook.
• Malacocarpus sessiliflorus (Hook.) Backeb.
• Notocactus sessiliflorus (Hook.) Krainz
• Wigginsia sessiflora (Hook.) D.M.Porter

• Parodia sellowii (Link & Otto) D.R.Hunt
• Echinocactus acuatus var. sellowii Speg.
• Echinocactus sellowii Link & Otto
• Echinocactus sellowii var. typicus Gürke
• Malacocarpus sellowianus Salm-Dyck
• Malacocarpus sellowii (Link & Otto) K.Schum.
• Melocactus sellowii Link & Otto
• Notocactus sellowii (Link & Otto) S.Theun.
• Wigginsia sellowii (Link & Otto) F.Ritter
• Parodia paucicostata (F.Ritter) F.H.Brandt ex Weskamp
• Wigginsia beltranii Frič ex Z.Fleisch. & Schütz
• Malacocarpus beltranii Frič
• Notocactus beltranii (Frič ex Z.Fleisch. & Schütz) G.Schäf.
• Notocactus sellowii var. beltranii (Frič) Neduchal
• Wigginsia bezrucii (Frič) Z.Fleisch. & Schütz
• Malacocarpus bezrucii var. Frič Frič
• Notocactus sellowii var. bezrucii (Frič) Neduchal
• Wigginsia bezrucii var. centrispina (Frič) Z.Fleisch. & Schütz
• Malacocarpus bezrucii var. centrispinus Frič
• Notocactus bezrucii var. centrispinus (Frič) S.Theun.
• Notocactus sellowii f. centrispinus (Frič) Neduchal
• Wigginsia corniger (Frič) Z.Fleisch. & Schütz
• Malacocarpus bezrucii var. corniger Frič
• Notocactus bezrucii var. corniger (Frič) S.Theun.
• Notocactus sellowii f. corniger (Frič) Neduchal
• Wigginsia bezrucii var. corniger (Frič) Z.Fleisch. & Schütz
• Wigginsia corynodes (Otto ex Pfeiff.) D.M.Porter
• Echinocactus acuatus var. corynodes (Otto ex Pfeiff.) Speg.
• Echinocactus corynodes Otto ex Pfeiff.
• Malacocarpus corynodes (Otto ex Pfeiff.) Salm-Dyck
• Notocactus acuatus var. corynodes (Otto ex Pfeiff.) Havlíček
• Notocactus corynodes (Otto ex Pfeiff.) Krainz
• Notocactus erinaceus f. corynodes (Otto ex Pfeiff.) N.Gerloff
• Wigginsia courantii (Lem.) F.Ritter
• Echinocactus courantii Lem.
• Echinocactus sellowii var. courantii (Lem.) Gürke
• Malacocarpus courantii (Lem.) Salm-Dyck
• Malacocarpus sellowii var. courantii (Lem.) Backeb. & F.M.Knuth
• Notocactus courantii (Lem.) S.Theun.
• Notocactus erinaceus subvar. courantii (Lem.) G.Schäf., G.Schäf.
• Notocactus sellowii var. courantii (Lem.) N.Gerloff
• Notocactus sellowii f. courantii (Lem.) N.Gerloff & Neduchal
• Wigginsia fricii (Arechav.) D.M.Porter
• Echinocactus fricii Arechav.
• Eriocactus fricii Arechav.
• Malacocarpus fricii (Arechav.) A.Berger
• Notocactus fricii (Arechav.) Krainz
• Notocactus sellowii f. fricii (Arechav.) N.Gerloff
• Wigginsia leucocarpa (Arechav.) D.M.Porter
• Malacocarpus leucocarpus (Arechav.) Backeb.
• Notocactus acuatus var. leucocarpus (Arechav.) Havlíček
• Notocactus leucocarpus (Arechav.) G.Schäf.
• Notocactus sellowii f. leucocarpus (Arechav.) N.Gerloff
• Wigginsia macracantha (Arechav.) D.M.Porter
• Echinocactus macrocanthus Arechav.
• Echinocactus sellowii var. macracanthus Arechav.
• Echinocactus sellowii f. macracanthus (Arechav.) Schelle
• Malacocarpus macracanthus (Arechav.) Herter
• Malacocarpus sellowii var. macrocanthus (Arechav.) Backeb. & F.M.Knuth
• Notocactus macracanthus (Arechav.) G.Schäf.
• Notocactus sellowii var. macracanthus (Arechav.) S.Theun.
• Notocactus sellowii f. macracanthus (Arechav.) N.Gerloff
• Wigginsia sellowii var. macracantha (Arechav.) F.Ritter
• Wigginsia macrogona (Arechav.) D.M.Porter
• Echinocactus macrogonus (Arechav.) Borg
• Echinocactus sellowii var. macrogonus Arechav.
• Echinocactus sellowii f. macrogonus (Arechav.) Schelle
• Malacocarpus macrogonus (Arechav.) Herter
• Malacocarpus sellowii var. macrogonus (Arechav.) Backeb. & F.M.Knuth
• Notocactus macrogonus (Arechav.) G.Schäf.
• Notocactus sellowii f. macrogonus (Arechav.) Havlíček
• Wigginsia pauciareolata (Arechav.) R.Kiesling
• Echinocactus pauciareolatus Arechav.
• Malacocarpus pauciareolatus (Arechav.) A.Berger
• Notocactus pauciareolatus (Arechav.) Krainz
• Notocactus sellowii f. pauciareolatus (Arechav.) N.Gerloff
• Wigginsia sesseliflora var. pauciareolata (Arechav.) Y.Itô
• Wigginsia rubricostata Frič ex Z.Fleisch. & Schütz
• Malacocarpus rubricostatus Frič
• Notocactus rubricostatus (Z.Fleisch. & Schütz) G.Schäf.
• Notocactus sellowii f. rubricostatus (Z.Fleisch. & Schütz) N.Gerloff in N.Gerloff, Neduchal & S.Stuchlik
• Wigginsia sessiliflora (Hook.) D.M.Porter
• Echinocactus sessiliflorus Hook.
• Malacocarpus sessiliflorus (Hook.) Backeb.
• Notocactus sessiliflorus (Hook.) Krainz
• Wigginsia sessiflora (Hook.) D.M.Porter
• Wigginsia sessiliflora var. martinii (Labour. ex Rümpler) D.M.Porter
• Echinocactus martinii (Labour. ex Rümpler) Cels ex K.Schum.
• Echinocactus sellowii var. martinii (Labour. ex Rümpler) K.Schum.
• Echinocactus sellowii f. martinii (Labour. ex Rümpler) Schelle
• Malacocarpus martinii Labour. ex Rümpler
• Malacocarpus sellowii var. martinii (Labour. ex Rümpler) Backeb. & F.M.Knuth
• Malacocarpus sessiliflorus var. martinii (Labour. ex Rümpler) Backeb.
• Wigginsia stegmannii (Backeb.) D.M.Porter
• Malacocarpus stegmannii Backeb.
• Notocactus sessiliflorus var. stegmannii (Backeb.) Havlíček
• Notocactus stegmannii (Backeb.) Krainz
• Wigginsia tephracantha (Link & Otto) D.M.Porter
• Echinocactus tephracanthus Link & Otto
• Malacocarpus tephracanthus (Link & Otto) K.Schum.
• Melocactus tephracanthus Link & Otto
• Notocactus erinaceus var. tephracanthus (Link & Otto) Krainz
• Notocactus sellowii f. tephracanthus (Link & Otto) Neduchal
• Notocactus tephracanthus (Link & Otto) Krainz
• Trichocereus tephracanthus (Link & Otto) Borg
• Wigginsia vorwerkiana (Werderm. ex Backeb.) D.M.Porter
• Echinocactus vorwerkianus Werderm.
• Malacocarpus vorwerkianus (Werderm.) Backeb.
• Notocactus sessiliflorus f. vorwerkianus (Werderm.) Neduchal

Description: Wigginsia sessifloraSN|20132]]SN|32063]] (a.k.a., Notocactus sessiliflorusSN|20136]]SN|20136]], or Malacocarpus sessiliflorusSN|20135]]SN|20135]]) is a local or morphological form of the widespread and variable Parodia sellowiiSN|20106]]SN|20106]]. It has spherical flattened stems, up to 20 cm in diameter with small yellow flowers about 25 mm wide, at the stem apex. However the distinguishing characteristics of Wigginsia sessifloraSN|20187]]SN|32063]], appear to fall within the natural variation of Parodia sellowiiSN|20106]]SN|20106]] and it should be synonymized with the latter. One of the typical features of (Wigginsia sessifloraSN|32063]]SN|32063]]), is the flower which is significantly smaller than most other Wigginsia, except only the closely related and very similar Wigginsia vorwerkianaSN|32063]]SN|20187]].
Stem: Spherical flattened, up to 200 mm wide, dark green, grey-green or brown-green. Ribs: Initially few, later up to 30, sharp, swollen around areoles.
Radial spines: Initially only 2-4, later 4-5, to 20 mm long, 3 curved downard.
Central spines: Nome, rarely 1. All spines dull white to horn coloured.
Flowers: Small about 25 mm wide, yellow; Petals lanceolate, tip somewhat rounded. The species is self-fertile.
Fruit: Pink.
Seeds: dark brown to black, 1.2 mm long and 1.1 mm wide.
Varieties: A few varieties namely var. debilacantha, var. martinii, var. paucicostata, var. stegmannii where previously assigned to Wigginsia sessilifloraSN|32063]]SN|20132]]. The last three varieties were sometimes considered separate species.

Bibliography: Major references and further lectures
1) Zulma E. Rúgolo de Agrasar, Pedro E. Steibel, Héctor O. Troiani “Manual ilustrado de las gramíneas de la provincia de La Pampa” Universidad Nacional de La Pampa, 2005
2) Havlíček R., “Notocactus (podrod Malacocarpus sensu Buxb.) sessiliflorus (Hook.) Krainz,” Kaktusy 79, 15 : 102-104, 1979
3) Mace T., “Notocactus - a review of the genus”, p. 68, 1978
4) Schäfer G., “Die Gattung Notocactus”, Kakteen, Sukkulenten, 14 : 93, 1979
5) Stuchlík S., “Představujeme zajímavé rostliny”, Minimus, 18 : 27, 1987
6) S.Stuchlíka, “WIGGINSIA SESSILIFLORA (Mackie ex Hook.) D.M.Porter var. SESSILIFLORA” retrieved 12 March 2016 from <http://www.cact.cz/galerie_test/detail.php?id=479>

Cultivation and Propagation: Wigginsia sessifloraSN|32063]]SN|32063]] is an easy to grow tropical cactus that like a warm bright location, but more cold tolerant than most. It requires a slightly acidic, permeable and nutritious substrate, regular watering and bright location.
Growth rate: It is a relatively rapidly growing and easily flowering species.
Soils: It prefer a very porous neutral to slightly acidic compost with plenty of extra grit.
Repotting: Use pot with good drainage.
Watering: Water regularly in summer, but do not overwater, keep dry in winter. It rot easily if the substrate is wet and cold, tends to lose its roots in winter. Best if watered with rain water.
Fertilization: Feed it once during the growing season with a fertilizer specifically formulated for cactus and succulents (poor in nitrogen), including all micro nutrients and trace elements diluted to ½ the strength recommended on the label. It thrives in poor soils and need a limited supplies of fertilizer to avoid the plants developing excess vegetation, which is easily attacked by fungal diseases.
Hardiness: Reputedly sensitive to frost , but less so if kept on the dry side prior to, and during, cold weather (hardy to -5° C for short periods). However warmth throughout the year will increase the grower's success (8-12°C during rest season).
Exposition: Outside bright filtered sunlight or afternoon shade, avoid full sun. Inside it needs bright light, and some direct sun. Subject to sunburn if exposed to direct sun for too long. Tends to bronze in strong light, which encourages flowering and heavy wool and spine production.
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: Sensitive to red spider mite. Overhead watering is helpful in controlling mites.
- Mealy bugs: Occasionally mealy bugs they 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 it 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: Direct sow after last frost. 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!