Key to Species

Ribs thick at base, triangular in cross-section.

Ribs 10 to 14 1. E. coptonogonus

Ribs about 35 2. E. hastatus

Ribs always numerous, very thin even at base.

Ribs 100 or more 3. E. multicostatus

Ribs 25 to 55.

Some or all of radial spines acicular or setaceous. Radial spines all acicular, white, straight. Flowers greenish yellow.

Central spines terete 4. E. wippermannii

Central spines narrow, but flattened 5. E. heteracanthus

Flowers not greenish yellow.

Central spines 4 6. E. albatus

Central spines 3.

Central spines annulate; apex of plant not depressed 7. E. lloydii

Central spines not annulate; apex of plant umbilicate 8. E. zacatecasensis

Upper radial spines subulate, some flattened. Spines yellow or white.

Spines only 5 or 6 9. E. lamellosus

Spines 8 to 11 10. E. grandicornis

Central and upper spines brownish 11. E. arrigens

None of the spines acicular.

Perianth-segments rather short.

All spines appressed against plant 12. E. violaciflorus

Some spines erect or porrect. Ribs about 25.

Four upper spines much elongated 13. E. obvallatus

Spines all somewhat similar.

Spines only 5 14. E. pentacanthus

Spines 10 or more 15. E. crispatus

Ribs 30 or more.

Radial spines white 16. E. dichroacanthus

Radial spines brown.

Flowers purplish 17. E. anfractuosus

Flowers yellow.

Upper and flattened spines 3, rather short, red 18. E. tricuspidatus

Upper and flattened spines usually 1, rarely 2 19. E. phyllacanthus

Perianth-segments much elongated and widely spreading or recurved 20. E. lancifer c • ^ 1 Í2I. E. gladiatus

Species not grouped

0 0

Post a comment