Origin and Habitat: This species is supposed to be endemic to Argentina, occurring between Tucumán and Salta. Echinopsis chamaecereus was collected by the botanist Carlo Spegazzini and described at the beginning of the XX century. However, the plant was never found again in the area during several expeditions on horseback by expert Roberto Kiesling, who only found in the area the widespread Echinopsis saltensis.
Habitat and Ecology: Because the species has not been found in the wild, the type of vegetation it grows in is unknown.

Synonyms:

• Cereus silvestrii Speg.
• Chamaecereus silvestrii (Speg.) Britton & Rose
• Lobivia silvestrii (Speg.) G.D.Rowley

Cultivation and Propagation: This is an easily grown cactus, suited to hanging baskets as well as pots. Grow in well-drained soil in a sunny spot. This Echinopsis needs a period of cool rest in winter to produce flowers abundantly. It flowers freely indoors if conditions suit it. The plant survives outside without protection in winter (cold hardy to -8° ) but somewhat prone to rot, then, too.
Needs moderate water in summer, none in winter Watch for infestations of mealybug, scale insects and spider mite.

Propagation:: Easy to propagate from offsets or seed. Small joints are produced in quantities (peanuts) These offsets can be detached and planted immediately as they root easily with no assistance when they touch the ground. Just let them lay on the soil and you have a new start.

Source: The Encyclopedia of Cacti

Scientific classification

Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Caryophyllales
Family: Cactaceae
Subfamily: Cactoideae

                         – Wikipedia.