Lobivia aurea fallax 
Bears strong spines and large silky yellow flowers. Superb plant!
 

Description: Solitary or branched.
Stems:  Dark green to grey-green globular or elongated reaching a height of 15cm and a diameter of 4 to 10 cm or more.
Ribs: 14 to 15 sharp-edged separated by deep grooves.
Spines: 8 to 10 radials clear radial about 2 cm. long pointing outward, usually 4 central spines, 3 to 6 cm long. The one to four central spines are thicker about 4 cm (up to 6cm) long, and brown to black with yellow tips.
Flowers: Lemon yellow and bright yellow inside (nearly 10 cm.) long. Blooms in flushes in late spring and occasionally in summer. Buds are covered by long silky hairs and grow laterally from the centre of the stem. The tube is slightly curved, funnel-shaped, slender and a greenish white, with pale green scales red at the base, with white and black down.
 

Cultivation: It is a summer grower species that offers no cultivation difficulties.  Water regularly in summer (but do not overwater ) It is rot prone and should be planted in a shallow pot. As most Echinopsis cultivated for their blossom, it needs a soil mixture a little richer than the average cactus with still an excellent drainage,  keep rather dry in winter.
It is quite frost resistant if kept dry, hardy to  -5°(-18°) C.  Need a very bright exposure, full sun is indispensable to keep plant compact with strong spines.

Propagation: Direct sow after last frost, offsets (if available)

Photo of conspecific taxa, varieties, forms and cultivars of Lobivia aurea (Echinopsis aurea). (This taxon has lots of synonyms (like most Lobivia) whit several controversial varieties and subspecies):

• Lobivia aurea
• Lobivia aurea var. fallax
• Lobivia aurea var. mizquensis
• Lobivia aurea var. shaferi

Origin: Northern Argentina

Synonyms:  

• Lobivia aurea var. fallax (Oehme) Rausch
• Echinopsis fallax var. shaferi,
• Lobivia fallax,
• Lobivia shaferi ssp. fallax,
• Echinopsis fallax,
• Pseudolobivia aurea var. fallax,

There are several varieties of L. aurea with very different spine shape and length.

 Lobivia aurea v fallax P137 La Rioja. Argentina
The spines are impressively strong and very showy. The spines of plants in cultivation are usually weaker because many growers fail to give them a full sun exposure.