mammillaria

From the genus name.

mammillaria (plural mammillarias)

1. (botany) Any member of the cactus genus Mammillaria.
   • 1841, John Claudius Loudon, The gardener's magazine and register of rural & domestic improvement, volume 7, page 511:

     For some years back collections of mammillarias, from whatever parts of the world they came, were grown in our hothouses, and many of them are still kept there.