Photo and © copyright by Andrea B. (Bologna, Italy)
A succession of large silky yellow flowers in summer.
 

Description: Habit: Solitary or slowly offsetting, globular.
Stem: Up to 15 cm tall, 10 cm in diameter; around 13 high wavy ribs, dark bluish green.
Areoles : 10-14 mm long, with short wool.
Spines: White or yellowish and brown, central 1 to 3 hooked (16 - 27 mm long); radials 12 to 16 (10-30 mm long)
Flower: Silky yellow with darker red throat , 3 - 4,2 cm across, 3,8 - 5,2(7) cm long.
Fruit: Red and fleshy, globular to ovate, 8-11 mm long, that dry and fracture basally at full maturity.
Seeds: 1,3-1,7 mm long and 0,5 -0,8 mm diameter.
Phenology: Summer grower. Blossoming time: Summer,  it flowers very well, even when quite young, producing  flowers in succession.
 

Cultivation: This species is easy and well worth growing. Require little care once they have reached a nice flowering size H. setispinus is suited for any rich, well drained soil in full sun throughout the year (But do better with some light shade in summer). Pot culture: grow best in a well-drained container filled with a porous cactus soil mixture that doesn't contain too much humus. To insure robust plants water and fertilize during the aestival growth cycle, this plant need plenty of water (indicatively to about once a week) But needs to be avoided wetting the bodies of these plants while they are in sunlight. A wet cactus in the sun light can cause sun burning which can lead to scars or even fungal infections and death. Care must be taken to prevent sooty mould forming on the sugary secretions from near the areoles.
Frost Tolerance: In winter keep completely dry at 5°C this usually aids in maintaining a healthier plant, but it is hardy as less as -12 to -7°C depending on the origin. (Temperature Zone: USDA 9-11)

Reproduction: Seeds or cutting. Seeds are the typical way of reproducing. These cacti will easily grow from seeds and some from cuttings. Seeds can be sown in the spring or summer in well-drained pots of cactus soil; sow the seeds thinly on top. Cover them with a bit of fine quartz grit. Moisten and lay a piece of glass across the top. The pots should be set in a warm greenhouse until they start to sprout, after which the glass should be progressively removed so they can receive full light and air.  It isn't good to keep the glass over the seedlings. Well-developed seedlings can be planted separately in small pots.
Cuttings made from pieces of the stem of any size can be detached and laid aside for a few days, to allow a protective "skin" to form over the cut. They can then be planted in pots. Place them in a spot where they'll receive sun, and do not water until the soil becomes fairly dry. After a while the soil should be moistened regularly, but never kept constantly saturated.
 

Scientific Name: Hamatocactus setispinus (Engel.) Britton & Rose 1922
Published in:  Britton & Rose, The Cactaceae; descriptions and illustrations of plants of the cactus family 3: 104-106, f. 110, 111, 112, 113, 114, 1922

Conservation status: Listed in CITES Appendix II

Distribution: USA (Southern-Texas) and Northern Mexico (Taumaulipas ; Nuevo Leon, Coahuila)

Habitat: Altitude 0 - 550m

Etymology:  The genus name " Hamatocactus" derives from the Latin word “Hamatus” meaning “fish-hook” to describe its central spines furnished of a terminal hook and the word "cactus", the genus from which this segregate was removed. ( The genus name implies: "hooked cactus"). 
The species name "setispinus" Derives from the Latin name “seta” meaning  “bristle” or “stiff hair of an animal” + “i” (connective vowel used by botanical Latin) + “spina” meaning “thorn, prickle, spine” + “us” (latinizing suffix) ( The specific name implies: " bristle-like spines ").

Synonyms:

• Thelocactus setispinus (Engelm.) E.F.Anderson
• Ferocactus setispinus,
• Echinocactus setispinus,

This plant, like the Ferocacti (within which genera some botanists place this plant, whilst some others prefer Thelocactus), has  areolar glands that produce nectar

.
The satiny yellow flowers have a contrasting red throats.
 

Photo of conspecific taxa, varieties, forms and cultivars of Hamatocactus setispinus:

• H. setispinus
• H. setispinus cv. brevispina