Cryptanthus Key by Marcelo de Senna Dias Candido for 43 species in Bromelia Vol2 #4 1995 and amended by Butcher to 59 species as at 2/2003
C. acaulis has been moved because of Luther's findings but C. bromelioides stays in the same relative position despite the fact that the revised description in Ramirez 1998 shows floral bracts as flat not carinate
| 1. | Petals | Free tip suborbiculate, Stigma with almost connate, straight lobes | 2 |
| Spatulate, apex acute to subacute, Stigma with free recurving lobes | 16 | ||
| 2. | Plant | Distinctly caulescent | 3 |
| Stemless or shortly caulescent | 5 | ||
| 3. | Leaves | With undulate margins, 1.5 to 2 cm wide | 6 |
| With straight margins | 4 | ||
| 4. | Leaves | Soft, Plant suggesting Pitcairnia (Domingos Martins, ES) | caulescens |
| Stiff, 15 -35cm long | 5 | ||
| Stiff, to 7cm long, strongly spined (ES) | microglazioui | ||
| 5. | Leaves | 0.7-1.2 cm wide and up to 15 cm long, sepals joined for 3-4mm (Santa Barbara, MG) | glazioui |
| With straight margins, 0.8 - 1cm wide, 20-35cm long, sepals free (Domingos Martins ES) | fernseeoides | ||
| 6. | Leaf blade | Up to 30 cm long (Santa Leopoldina, ES) | exaltatus |
| 5-12 cm long | 6a | ||
| 6a. | Leaf blade | 1.5cm wide, 7 fascicles, sepals connate 7 - 7mm (Santa Leopoldina, ES). | pseudoglaziovii |
| 2cm wide, 10 fascicles, sepals connate 2mm (Domingos Martins ES) | leuzingerae | ||
| 7. | Leaves | Glabrous to glabrescent adaxially | 8 |
| Densely lepidote on both sides | 13 | ||
| 8. | Leaves | Bearing distinct dark-brown crossbands abaxially (Domingos Martins, ES) | roberto-kautskyi |
| Evenly lepidote abaxially, without any crossbands | 9 | ||
| 9. | Leaf blade | Lanceolate to broadly lanceolate | 10 |
| Narrow, linear-lanceolate | 11 | ||
| 10. | Leaf blade | ca. 2,5 cm wide. (Domingos Martins, ES) | pseudoscaposus |
| 5-7 cm wide (Guarapari, ES) | latifolius | ||
| 3.5-5.5cm wide at 2/3rds length, petals green (Vitoria ES) | grazielae | ||
| 11. | Leaf margins | Distinctly undulate (Santa Leopoldina, ES) | odoratissimus |
| Straight | 12 | ||
| 12. | Leaf spines | 1mm long. (Domingos Martins, ES) | scaposus |
| Acicular, 2-3 mrn long. (Minas Gerais) | schwackeanus | ||
| 13. | Leaf spines | 0.5 mm long. (Domingos Martins, ES) | whitmanii |
| Over 1mm in length | 14 | ||
| 14. | Leaf spines | Retrorse (Diamantina, MG) | warasii |
| Dentate, or with acicular spines | 15 | ||
| 15. | Leaves | Nervate abaxially, margins with acicular spines.(Santa Barbara, MG) | caracensis |
| Not distinctly nervate abaxially, margins with dentate-triangulate spines (Diamantina, MG) | leopoldo-horstii | ||
| 16. | Leaves | Striped adaxially | 17 |
| Without stripes adaxially | 28 | ||
| 17. | Leaves | With lepidote crossbands adaxially | 18 |
| With stripes longitudinal | 20 | ||
| 18. | Sepals | Serrulate (S. Bento, PE) | fosterianus |
| Entire | 19 | ||
| 19. | Plant | Propagating by axillary shoots, never stoloniferous (Recife, PE) | zonatus |
| Stoloniferous, stolons 10-20 cm long (Gravata, PE) | burle-marxii | ||
| 20. | Stripe | Single, median, pale colored | 21 |
| Stripes | 2 or more | 26 | |
| 21. | Sepals | Serrulate (Itabirito, MG) | minarum |
| Entire | 22 | ||
| 22. | Leaf margins | Mostly entire, serrulate near the apex only (Marau, BA) | ruthiae |
| Serrulate throughout | 23 | ||
| 23. | Leaf blade | Glabrous adaxially | 24 |
| Not totally glabrous | 25 | ||
| 24. | Leaf blades | 2-3cm wide, 24cm long, Sepals 4mm long (Ubaira BA) | ubairensis |
| To 2cm wide, 17cm long, Sepal 11mm long (ES) | praetextus | ||
| 25. | Leaf blade | Lepidote to glabrescent adaxially (Sao Lourenco da Mata, PE) | pickelii |
| Lepidote near base, glabrous to apex (Caete - Acu BA) | diamantinensis | ||
| 26. | Leaf blade | Glabrous adaxially | bivittatus |
| Partially lepidote adaxially | 27 | ||
| 27. | Trichomes | On leafbase only (Santa Teresa, ES) | marginatus |
| Arranged in three longitudinal stripes | lacerdae | ||
| 28. | Leaves | With contrasting color and indumentum above and below | 29 |
| Densely lepidote on both sides | 45 | ||
| 29. | Leaves | Distinctly petiolate | 29a |
| Not petiolate | 30 | ||
| 29a. | Petioles | Distinctly terete (tubular) ( Vitoria ES) | teretifolius |
| Only channelled | 29b | ||
| 29b. | Leaves | Broadly lance-ovate, 4-5cm wide, blotched or uniformly green adaxially (ES) | beuckeri |
| Linear lanceolate, to 2cm wide (Jaguaripe BA) | lyman-smithii | ||
| 30. | Floral bracts | (Hermaphroditic! or outer fascicles) shorter than the ovary | 31 |
| (Hermaphroditic! or outer fascicles) equal to exceeding the ovary | 32 | ||
| 31. | Plant | Caulescent, leaf blade minutely and densely serrulate, spines less than 0.5 mm long (Domingos Martins, ES) | correia-araujoi |
| Stemless, leaf blades serrulate, spines 1 mrn long (Vitoria, ES) | incrassatus | ||
| 32. | Floral bracts | Outer fascicle carinate | 33 |
| Outer fascicle ecarinate | 42 | ||
| 33. | Leaves | Not constricted between blade and sheath | 34 |
| Distinctly narrowed between blade and sheath | 36 | ||
| 34. | Leaves | 20-45cm long, 2-4cm wide | 35 |
| 45-80cm long, 1-2cm wide, plant to 80cm tall (Amarelo ES) | lutherianus | ||
| 35. | Petals | Acuminate (Milagres, BA) | seidelianus |
| With rounded apex (Serra, ES) | coriaceus | ||
| 36. | Leaf blade | 50-75 cm long | 37 |
| 30-40cm long (Palmeiras, BA) | arelii | ||
| Up to 30 cm long | 38 | ||
| 37. | Petals | Bearing two well developed calluses at base(Aracruz,ES) | capitatus |
| Bearing two inconspicuous calluses at base (Paripuera, AL) | alagoanus | ||
| Without calluses (Una, BA) | pseudopetiolatus | ||
| 38. | Sepals | Connate at base only | osiris |
| Connate to half their length or more | 39 | ||
| 39. | Leaf margins | Entire at apex | delicatus |
| Entirely serrulate | 40 | ||
| 40. | Fascicles | With 4-6 flowers, leaf margins minutely serrulate (Rio de Janeiro, RJ) | bromelioides |
| With 3 flowers. | 41 | ||
| 41. | Petals | With calluses at base | 41a |
| Without calluses at base | 41b | ||
| 41a. | Petals | Bearing small calluses at base (Itaberaba, EA) | warren-loosei |
| Bearing large calluses at base (Itapetinga, BA) | bibarrensis | 41b. | Petals | White (Pres. Kennedy, ES) | dorothyae |
| White with green tip (Itapetinga, BA) | reisii | ||
| 42. | Plant | Caulescent, stem to 40cm x 10-15mm diam, leaves up to 40 cm x 12-20mm, canaliculate (Bahia) | bahianus |
| Caulescent, stem to 35cm x 20-30mm diam, leaves up to 46cm x 15-16mm, (San Luzia do Itanhi, SE) | sergipensis | ||
| Stemless or shortly caulescent | 43 | ||
| 43. | Leaves | Mostly erect, linear-lanceolate (Vitoria, ES) | maritimus |
| Recurvate | 44 | ||
| 44. | Leaf blades | ca. 1.2 cm wide (Potiragua, EA) | colnagoi |
| 2-3 cm wide Flowers ca. 2.3 cm long, sepals serrulate or rarely entire (Rio de Janeiro,RJ) | sinuosus | ||
| 45. | Plant | Caulescent | 46 |
| Stemless, leaves over 15cm long | 47 | ||
| Stemless, leaves to 10cm long (Rio de Janeiro RJ) | acaulis | ||
| 46. | Sepals | Connate to half their length or more | diversifolius |
| Connate near the base only (Una, BA) | vexatus | ||
| 47. | Floral bracts | Entire or nearly so (Santa Cruz da Vitoria BA) | argyrophyllus |
| Serrulate (Ceres GO) | dianae |