Key to the Turbinicarpus species

To make best use of this key you should have mature, ungrafted plants that you wish to identify. This is especially the case with species of Turbinicarpus sensu Franz Buxbaum and Curt Backeberg, i.e.. the current genus Turbinicarpus excluding the old separate genera Gymnocactus and Rapicactus, because of the phenomenon of neoteny in Turbinicarpus. Ungrafted plants should be used as grafted plants tend to become bloated and do not give a good representation of how the plants look on their own roots.

This key is based on keys from "A revision of the genus Turbinicarpus", CASJ(US),49(4):1977, by Charles Glass and Robert Foster, Las Cactáceas De México by Helia Bravo-Hollis and Hernando Sánchez-Mejorada and A revision of the genus Neolloydia by E. F. Anderson.

If the description of a taxa is available a link is included to a separate document. This document will include further information such as a full description, photos and notes specific to that species and related taxa. A glossary of botanical terms is also available.

Key to the "sub-genera" of Turbinicarpus

Bodies to 6 cm Ø, tubercles small, spination of mature plants plumose or pectinate: Pelecyphora / Normanbokea
Bodies to 7 cm Ø, tubercles usually large and low, spination usually thick, sparse and mostly early deciduous, crown bare or with some wool: Turbinicarpus
Bodies to 9 cm Ø, tubercles fairly slender, spination fine, dense and persistent, crown with conspicuous light coloured wool: Gymnocactus

Key to the species of Turbinicarpus

Spines pectinate or plumose only on juvenile specimens; central spines generally present:
- Spines papery or cardboard-like:
  - Tubercles as long as they are broad, body flattened (similar to Ariocarpus spp), flower purple: T. alonsoi
  - Tubercles longer than broad:
    - Spines thick, cardboard-like, flowers white with pink mid-stripe: T. schmiedickeanus
    - Spines thin, papery, flowers white: T. schmiedickeanus ssp. gracilis
    - Spines thin, papery, flowers yellow: T. schmiedickeanus ssp. flaviflorus
  - Tubercles broader than long:
    - Tubercles pronounced conical, more or less ascending:
      - Tubercles elongated, over 5 mm long, spines 2.5 to 4 cm long: T. macrochele
      - Tubercles short, under 5 mm long, spines short, under 1 cm long: T. schmiedickeanus ssp. klinkerianus
      - Tubercles short, under 5 mm long, single central, strongly appressed: T. schmiedickeanus ssp. andersonii
      - Tubercles short, spines 1.2 to 1.5 mm long: T. schmiedickeanus ssp. bonatzii
    - Tubercles more or less flattened:
      - Body appears to be covered in "specks", single central spine tipped black: T. lophophoroides var jauernigii
      - Body pale green, spines yellowish brown, to 2.0 cm long, flowers white: T. schmiedickeanus ssp. klinkerianus fa. schwarzii
      - Body pale green, spines yellowish brown, to 2.5 cm long, flowers pink: T. schmiedickeanus ssp. rubriflorus
      - Body brownish, similar in appearance to a Lophophora spp.: T. macrochele ssp. macrochele var. polaskii
      - Body matt green, flowers white: T. schmiedickeanus ssp. rioverdensis
- Spines not papery or cardboard-like:
  - Spines slightly curved, more or less stiff:
    - Radial spines numerous (to 20) : T. dickisoniae
    - Radial spines few or lacking:
      - Stem under 3.5 cm Ø, greenish, spines 6 to 7: T. laui
      - Stem up to 4.5 cm Ø, bluish, spines to 4: T. lophophoroides
      - Stem up to 5 cm Ø, dark greyish green - pale bluish green (turning brownish in the sun), spines 4 to 6, tipped darker: T. swobodae
      - Stem up to 7 cm Ø, greyish green, spines 4 to 7, tipped darker: T. hoferi
- Spines tortuous and more or less hair-like:
  - Stem pale green, rounded tubercles
    - Root and body not easily discernible, flowers 3.5 cm Ø, perianth segments white with rose mid-stripe: T. pseudomacrochele var. pseudomacrochele
    - Root and body separated by slight constriction, flowers to 4.5 cm Ø, perianth segments pink: T. pseudomacrochele var. sphacellatus
  - Stem dark green, conical tubercles, flowers 2 cm Ø
    - perianth segments pink: T. pseudomacrochele ssp. krainzianus fa. lausseri
    - perianth segments greenish to yellowish cream:
      - Body greater than 12 mm diameter: T. pseudomacrochele ssp. krainzianus
      - Body up to 12 mm diameter: T. pseudomacrochele ssp. krainzianus fa. minimus

Key to the species of Pelycyphora / Normanbokea

Spines pectinate or plumose even on mature specimens, central spines absent:
- Spines plumose:
  - Flowers pink-purple: T. valdezianus
  - Flowers white: T. valdezianus var. albiflorus
- Spines pectinate:
  - Flowers whitish and/or with magenta/purple mid-stripe: T. pseudopectinatus
  - Flowers magenta/purple: T. pseudopectinatus ssp. jarmilae

Key to the species of Gymnocactus (incl. Rapicactus)

Body separated from the tap root by a very thin, woody section: (Rapicactus)
- Root with long neck (up to 10 cm long), central spines 2, 1 pointing towards crown, radial spines 16 to 25, flowers magenta: T. mandragora ssp. subterraneus
- Root with short neck (less than 10 cm long), central spines 2, pointing away from the body, radial spines 21 to 25, flowers brownish yellow: T. mandragora ssp. zaragozae
- Root with short neck, radial spines to 14, flowers white with reddish mid stripe: T. mandragora
- Root with short neck, (1 to 5cm long), radial spines mostly 18 to 20, flowers dark magenta: T. mandragora ssp. booleanus
Body and tap root continuous: (Gymnocactus)
- Central spine absent or 1
  - Radial spines 6 to 12, flowers 2 to 4 cm long.
    - Radial spines 6 to 8, flowers white: T. gielsdorfianus
    - Radial spines mostly 12, flowers violet to brownish inside: T. mandragora ssp. beguinii
    - Radial spines 9 to 12, flowers intensive red colour purple: T. horripilus
  - Radial spines 16 to 20
    - Spines to 7 mm long, flowers short, 1 to 1.5 cm long, interior perianth segments white colour ivory: T. saueri ssp. ysabelae
    - Spines under 7 mm long, flowers short, 1 to 1.5 cm long, interior perianth segments white colour ivory: T. saueri ssp. ysabelae (var. brevispina)
    - Flowers longer, 2 to 3 cm long, interior perianth segments whitish colour dye violet rose: T. knuthianus
- Central spines 2 or more
  - Radial spines 12 to 16
    - Interior perianth segments white or pink white with pink mid line.
    - Central spines 2, of obscure chestnut-coloured colour; vitreous radial spines, white: T. saueri
    - Central spines 4, in cross formation, flowers white: T. viereckii ssp. major
  - Radial spines about 20, central spines 4, interior perianth segments violet rose: T. viereckii

References

Cactus Lexicon - by Curt Backeberg.
A revision of the genus Turbinicarpus, CASJ(US),49(4):1977 - by Charles Glass and Robert Foster.
Las Cactáceas De México - by Helia Bravo-Hollis and Hernando Sánchez-Mejorada.
A revision of the genus Neolloydia by E. F. Anderson.

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