Eriosyce clavata
Plant belonging to this taxon have about 11 to 13 thick radial spines per areole and slender stems with age.
 

Description: The Eriosyce clavata  is one of the innumerable and controversial form and variety of Eriosyce subgibbosa which is a very variable species that and has received numerous names. It is one of the few species that forms cylindrical stems.
Stem: Solitary, but sometimes branched, globular to columnar, up to 90 cm tall (or more), up to 10 cm wide. Grey-green, brownish-green or blackish-green. ("clavata" means "club shaped" and refers to the usually cylindrical stem shape of this form)
 Ribs: ± 20
 Spines: Nearly hiding the ribs, acicular, more or less long and dense, white, yellowish, golden yellow, brown, or nearly black, while older one became greyish.
 Radial spines: 8-30, radiating,
 Central spines: 4 (or more) stronger, straight or recurved  and spreading, often darker at the tips..
 Flower: Pretty relatively small up to about 4 cm long, bi-coloured with magenta, rose to the violet petal tips and pinkish-white, white or yellowish-white throat, giving the sensation of being fluorescent and being very difficult to photograph in good conditions because that particularity.
Blooming season: Blooms early in late winter to spring. It is advisable to leave them dry from middle of November to obtain fantastic flowering later in January/March.
Fruits: Ovoid to cylindrical, partly hollow at maturity, only scarcely woolly, apical areoles not spinescent.

Recognized subspecies, varieties and forms:

Eriosyce subgibbosa var. subgibbosa (Haworth) F. Kattermann. This is the form with more elongated stems, with 8 to 30 thin, acicular, radial spines per areole, spines often yellowish
Eriosyce subgibbosa var. castanea (F.Ritter) Katt. It has thin short and acicular radial spines and globose stems that will sometimes offset. The flowers can get up to 6 cm long (the larger among the "subgibbosa" forms).
Eriosyce subgibbosa var. litoralis (F.Ritter) Katt. It is very spiny and has from 30 to 40 hairlike radial spines per areole it grows in the rocks,
Eriosyce subgibbosa ssp. clavata (Söhrens ex K.Schum.) Katt. It has from 11 to 13 thick radial spines per areole and slender stems.
Eriosyce subgibbosa ssp. clavata var. nigrihorrida (Backeb.) Katt. It has dark coloured radial spines and globose stems most of the time.
Eriosyce subgibbosa ssp. clavata var. vallenarensis (F.Ritter) Katt. it has from 9 to 24 thin & straight radial spine per areole and slender stems.
Eriosyce subgibbosa ssp. clavata var. wagenknechtii (F.Ritter) Katt. It has dark skin and smaller pink flowers than the other varieties at about 3 cm cm wide.
 

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Scientific name:  Eriosyce clavata ( Söhrens ex K.Schum. ) Helmut

Nowadays regarded as: Eriosyce subgibbosa var. clavata (Söhrens ex K.Schum.) F.Kattermann

Conservation status: Listed in CITES appendix 2.

Origin:  Coastal Chile (Approx from Valparaiso to Maule)

Habitat:  Grows on rocky outcrop on costal terraces cliffs, slopes, often hanging from rocks, from areas with very arid Mediterranean climate to areas of transition between Mediterranean climate and humid forest.

Synonyms:

• Echinocactus subgibbosus Haw.
  [Philos. Mag. 10:419. 1831]
• Eriosyce subgibbosa (Haw.) Katt.)
• Neoporteria subgibbosa (Haw.) Britton & Rose)

Cultivation:  It is a summer grower species. Easy to cultivate but somewhat rot prone if kept in a non ventilated place. Require a very fast draining drying soil, water regularly in summer, but do not over-water.
Needs a full sun exposure (or light shade)  Good heat tolerance. Hardy to at least -5°C ( but probably can tolerate - 10° C for brief periods)

Propagation: Usually propagated from Seeds.  (seldom produces offsets)

Photo of conspecific taxa, varieties, forms and cultivars of plants belonging to the Eriosyce subgibbosa complex  (This taxon has lots of synonyms (like most Eriosyce), with several controversial varieties and subspecies):