Frailea angelesii

Frailea angelesii
On beautiful summer days one can admire the splendour of its beautiful yellow flower, larger than the plant itself.  The diminutive stem is a splendid shining dark-purple, with ginger spines.
 

Description: F. angelesii is a miniature slow-growing species.  It branches from the base, and eventually produces small clumps .
Stem: It is diminutive in size, shortly columnar, shiny dark-purple or dark-brown, up to 3 cm in height (or more in cultivation), 2-2,5 cm in diameter.
Ribs: About 13, with round and tapering tubercles.
Areoles: Placed on the upper side of the tubercles.
Spines: Ginger coloured, spreading, thin, 1,5-3 mm long.
Roots: Fat central tap root.
Flowers: Infundibuliform, larger than the plant itself, sulphur-yellow, 2,5 cm in diameter. But don't be disappointed when the easily produced buds fail to open.
Fraileas are cleistogamous, meaning that their flowers are internally pollinated and produce seed without even opening.  Without the need for pollination, the buds rarely reach full bloom and remain closed.  They will open only in great heat, in the hottest, brightest, afternoon sun, if at all.
Fruit: Dry, indehiscent, that detach easily, pericarp membranous, fragile that break easily, releasing the seed.

Notes: This plant is short-iving (It only lives about 10-15 years).

Scientific Name: Frailea angelesii R. Kiesling ex K.H. Prestlé
In: Gattung Frailea (Br. & R.) Prestlé: 52, without latin descr. or type, 1997

Etymology: The genus name "Frailea" remembers the Spanish "Manuel Fraile", born in 1850, who was responsible for the cactus collection of the United States Department of Agriculture  at the end of the XIX century.
The species name name "angelesii"  derives from the wife of the argentine botanist  Roberto Kiesling, Angeles (with a wrong Latin termination)

Frailea angelesii is an odd & very showy species with very dark heads. Eventually it will form small clumps.

Cultivation:  Grow them in rich, porous soil and let them dry out between waterings.  These plants need a minimum temperature of 5-10° C (but occasionally temperatures of a few degrees below 0° are not dangerous)
Sun Exposure:  It enjoys full sun, and it can take on a nearly black appearance when kept in bright light.  In a shaded position the plants grow faster, but are not flat shaped or dark coloured.
Characteristically, during the dry season plants retract completely under the ground, both in the wild and in cultivation too.

Propagation:  With fresh harvested  seeds or (rarely) by grafting.