The flowers are large silky pink with a red throat.

Description: Usually solitary.
Stem: Large, globular, low-growing, green, reach hardly 15 cm in diameter and get 10-15 cm tall.  Epidermis - bluish-sulphur- green that became almost red-brown during the winter rest when the plants are dry.
Tubercles: Rounded that form 8-11 (usually 9) distinct ribs.
Areoles: Round, on the outer side of tubercle bear semicircular heavy cut.
Spines: 7-11 (-19), powerful, very different in length, thickness and colour.
Central spines: 1-2 (or more) bent back and newly bent to the body the upper one is flattened, red- white colored, the spines produced in spring are brighter and redder while the one produced the hot period of year are paler, some plants have very short spines, whose central prickle has a length of only of 1,5 cm, but there are plants with 5,5 cm long spines. The name "heterochromus" (= many-colored) indicates patch effect of prickles, but it can be also applied to the variable colours of spines in different plants.
Radial spines: 9-11 (-18) 1,5-3 cm long, yellowish strong, awl-shaped, usually bent downward.
Flowers: Imposing 8-10 cm in diameter pink-violet lobes with a dark red throat and yellowish orange anthers.
Blooming season: Flowers appear exclusively from June through August.
 

Cultivation: It is a summer grower species easy to cultivate. Water regularly from Spring to Autumn, but do not overwater, can become too elongated if compost is too rich. Requires full sun or light shade and careful watering to keep plant compact with strong coloured spines. Needs good drainage and very porous potting mix, In Winter, keep dry.

Reproduction: From seed, since the plant rarely produces plantlets.

This is one of most beautiful Thelocactus. But, unfortunately, this plant is supplied only, rarely, sometimes by the name Thelocactus heterochromus.

Conservation status: Listed in CITES appendix 2

Origin: Northeastern Mexico (Chiuaua and coahuila) Like many cactus forms of this dry, hot region of Mexico, plants are strongly variable; therefore a precise description is impossible.

 

Synonyms:

• Echinocactus pottsii Salm-Dick
  In: "Allgemeinen Gartenzeitung 1850
• Thelocactus pottsii (Salm-Dyck) Britton & Rose 1923
• Echinocactus heterochromus F. A. C. Weber
  In: " French garden lexicon " 1896
• Thelocactus heterochromus (F. A. C. Weber) van Oosten 1940
• Echinocactus bicolor [var.] pottsii Salm-Dyck 1850
• Ferocactus heterochromus (F. A. C. Weber) N. P. Taylor 1979

Photo of conspecific taxa, varieties, forms and of plants belonging to the Thelocactus bicolor complex (This Taxon has lots of synonyms ( like many other cacti) whit several controversial varieties and subspecies and comprises a multitude of different forms, but where each form is linked to others by populations of plants with intermediate characteristics):

• T. bicolor var. bicolor (Frost hardiness -7°C )
• T. bicolor var. bolaensis (Frost hardiness -12°C ) Origin: Coahuilafrom Sierra Bola, up to 20 cm tall.
• T. bicolor var. commodus  It has been described as having only one, porrect, central spine, but with a careful observation it is possible to notice that the upper central spines are so appressed to the stem that they can be easily mistaken for radials.
• T. bicolor var. ellipticus is referable to bicolor.
• T. bicolor var. flavidispinus (Frost hardiness -12°C ) Texas 8cm in diameter, 5cm tall.
• T. bicolor var. heterochromus
• T. bicolor var. pottsii (Referable to bicolor var. heterochromus).
• T. bicolor var. rhodophthalmus is referable to bicolor.
• T. bicolor var. schottii (Frost hardiness -12°C) coming from the Big Bend area Texas, Chihuahua) characterized by a very long, papery upper spine.
• T. bicolor var. schwarzii 1 0° F (-12°C) Tamaulipas
• T. bicolor var.  texensis is an invalid name for a Texas form.
• T. bicolor var. tricolor (Frost hardiness -7°C ) A form with bright red spines. Plants with these characters can be found around Saltillo, Coahuila.
• T. bicolor var. zwakii,  It is not sufficiently distinct to deserve a subspecies rank.

Cultivars: Thelocactus bicolor cv. INERMIS