Origin and Habitat: Endemic of Magdalena Island and Llano de la Magdalena, Baja Caifornia
Habitat: On sandy plains and coastal sand dunes

• Mammillaria voburnensis var. quetzalcoatl Repp.

• Mammillaria karwinskiana Mart.
• Cactus karwinskianus (Mart.) Kuntze
• Neomammillaria karwinskiana (Mart.) Britton & Rose
• Mammillaria confusa (Britton & Rose) Orcutt
• Mammillaria pyrrhocephala var. confusa (Britton & Rose) Borg
• Neomammillaria confusa Britton & Rose
• Mammillaria confusa var. centrispina R.T.Craig
• Neomammillaria confusa var. centrispina (R.T.Craig) Y.Itô
• Mammillaria confusa var. robustispina R.T.Craig
• Mammillaria conzattii (Britton & Rose) Orcutt
• Mammillaria confusa var. conzattii (Britton & Rose) R.T.Craig
• Neomammillaria conzattii Britton & Rose
• Mammillaria ebenacantha Shurly
• Mammillaria fischeri Pfeiff.
• Cactus fischeri (Pfeiff.) Kuntze
• Mammillaria jozef-bergeri Wojnowski & Prajer
• Mammillaria karwinskiana var. virens (Scheidw.) Salm-Dyck
• Cactus virens (Scheidw.) Kuntze
• Mammillaria virens Scheidw.
• Mammillaria multiseta Ehrenb.
• Mammillaria nagliana Repp.
• Mammillaria neomystax Backeb.
• Neomammillaria neomystax (Backeb.) Y.Itô
• Mammillaria neomystax var. rhodacantha Y.Itô
• Neomammillaria neomystax var. rhodacantha (Y.Itô) Y.Itô
• Mammillaria praelii Muehlenpf.
• Cactus praelii (Muehlenpf.) Kuntze
• Mammillaria viridis var. praelii (Muehlenpf.) Salm-Dyck
• Neomammillaria praelii (Muehlenpf.) Britton & Rose
• Mammillaria strobilina Tiegel
• Mammillaria tropica Repp.

• Mammillaria karwinskiana subs. beiselii (Diers) D.R.Hunt
• Mammillaria beiselii Diers

• Mammillaria karwinskiana subs. collinsii (Britton & Rose) D.R.Hunt
• Mammillaria collinsii (Britton & Rose) Orcutt
• Mammillaria voburnensis subs. collinsii (Britton & Rose) U.Guzmán
• Mammillaria voburnensis var. collinsii (Britton & Rose) Repp.
• Neomammillaria collinsii Britton & Rose
• Mammillaria voburnensis var. quetzalcoatl Repp.

• Mammillaria karwinskiana subs. nejapensis (R.T.Craig & E.Y.Dawson) D.R.Hunt
• Mammillaria nejapensis R.T.Craig & E.Y.Dawson
• Mammillaria nejapensis f. aureispina (Y.Itô)
• Neomammillaria nejapensis var. aureispina Y.Itô
• Mammillaria nejapensis f. brevispina (R.T.Craig & E.Y.Dawson) Krainz
• Mammillaria nejapensis var. brevispina R.T.Craig & E.Y.Dawson
• Neomammillaria nejapensis var. brevispina (R.T.Craig & E.Y.Dawson) Y.Itô
• Mammillaria nejapensis f. elegans (Y.Itô)
• Neomammillaria nejapensis var. elegans Y.Itô
• Mammillaria nejapensis f. longispina (R.T.Craig & E.Y.Dawson) Krainz
• Mammillaria nejapensis var. longispina R.T.Craig & E.Y.Dawson
• Neomammillaria nejapensis var. longispina (R.T.Craig & E.Y.Dawson) Y.Itô
• Mammillaria nejapensis var. typica R.T.Craig & E.Y.Dawson

Description: This is one of strangest of all cacti with strongly armed prostrate stems except for their slightly raised tips. They grow about up to 3 m long, 4-8 cm in diameter and take root as they creep, ramifying further and eventually covering a huge area. Sometimes plants separate from the parent stem and spread out around it, leaving it to die. Stems have 12 ribs; large areoles, 2 cm apart; 1 central and flat spine much wider than the others, 3 cm long, and around 20 light grey or whitish radials of unequal length. Outer ones are short and subulate; inner ones are larger and flat.

Bibliography: Major references and further lectures
1) Edward F. Anderson “The Cactus Family” Timber Press, 2001
2) James Cullen, Sabina G. Knees, H. Suzanne Cubey “The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass” Cambridge University Press, 11/Aug/2011
3) David Hunt, Nigel Taylor “The New Cactus Lexicon” DH Books, 2006 ISBN 0953813444, 9780953813445
4) Walther Haage “Kakteen von A bis Z” Neumann Verlag, 1981

Cultivation and Propagation: This plant, which is seldom cultivated, needs very sandy soil and should be placed in a semiprostrate position so that it may creep.
Propagation: Propagation is usually by cuttings or seed