Mammillaria luethyi forma cristata

Cristation in this plant is unstable and defasciation occurs all the times.  
That is the linear meristem turns into a number of small apical meristems that form normal shoots.
 

Notes: The defasciation is a process leading to longitudinal cleavage of a linear crest, rather to the complete division of the stem into individual normal shoots. Crests may remain at any stage for a long time. But at the stage of brain-shaped crest when the curves begin to crowd defasciation occurs rather often. That is the linear meristem turns into a number of small apical meristems that form normal shoots. More seldom defasciation occurs without any reason at an earlier stage of the development of the crest.

Family: Cactaceae (Cactus Family)

Scientific name:  Mammillaria luethyi,
Published by G.S. Hinton in Phytologia, January 1996.

forma cristata.

Origin:  Garden origin (Nursery produced cultivar)

Conservation status: Listed in CITES appendix 2.

A small crest grafted on  Opuntia compressa

Photo of conspecific taxa, varieties, forms and cultivars of Mammillaria luethyi:

• M. luethyi
• M. luethyi cristata