This follows roughly the information given in the Monograph by Smith and Downs (Flora Neotropica no. 14, 1974 - 77) which covered 46 genera. This was expanded in Lyman Smith's paper in Beitr. Biol. Pflanzen 63 (1988) 403 - 411 to cover 51 genera where he added new genera Steyerbromelia, Brewcaria, Pseudaechmea, and Lymania. Lindmania was revived from synonymy of Cottendorfia. In the same issue but on pages 101 - 113 Elvira Gross reported findings on the germination processes of the three subfamilies and one facet is shown in the key below. The key was further updated in 1998 by L. B. Smith and W. Till to cover 56 genera in The Families and Genera of Vascular plants, Kubitzki pages 83 - 86 (1998) where Alcantarea, Werauhia, Ursulaea, Pepinia, and Racinaea were added. Abromeitiella had been placed in synonymy under Deuterocohnia Note that Streptocalyx was retained purely because the genus Aechmea is currently in a state of flux. From a horticultural point of view the retention of this genus tends to make sense because of the similar growing conditions needed to get good specimens. However, Chevaliera was resurrected to genus status because of its clearly delineated boundaries and is said to be more of a natural group. Since this publication the genera have increased to 58 where Derek Butcher has now added Canistropsis, and Edmundoa, and made adjustments to Canistrum, Nidularium, and Wittrockia because of Elton Leme's recent work Canistrum - Bromeliads of the Atlantic Forest (1997) and Canistropsis - Bromeliads of the Atlantic Forest (1998). The merging of Pepinia into Pitcairnia at generic level in Harvard Papers in Botany Vol. 4 no.1 195 - 202 (1999) by Robinson and Taylor has reduced the genera to 57.
The splitting of Vriesea from Tillandsia is based on petal appendages in couplet 21. The process of re-evaluating the Tillandsioideae has been accomplished so far with the acceptance of Alcantarea, Racinaea, and Werauhia Some taxa, for example Tillandsia engleriana and Tillandsia myriantha have petal appendages and should be treated as Vriesea in the strict sense, but sit comfortably in the Tillandsia sub-genus Allardtia.
The splitting of Portea from the rest is based on pedicellate flowers in couplet 53 but there is an exception in the taxon which has all the attributes of a Portea but was described as Aechmea rubrolilacina indicating that the Bromelioideae also needs review.
THE KEY.
| 1. | Mature seed appendaged or if not (Pitcairnia in part and Navia and Brewcaria), then the fruit capsular and dehiscent; ovary superior or largely so in most genera to inferior; fruit capsular or if not (Pitcairnia in part), then the seed appendaged. | 2 |
| 1a. | Mature seed unappendaged; fruit baccate; ovary inferior; leaves mostly spinose-serrate; indument almost always of obvious scales; on seed germination the cotyledon remains in the seed; plants often terrestrial. (subfamily. Bromelioideae) |
26 |
| 2. | Seed appendages entire or slightly divided (Brocchinia paniculata) or lacking (Pitcairnia aphelandriflora) and (Navia); fruit usually dehiscent; leaves mostly spinose-serrate; indument of finely to scarcely divided scales; on seed germination the cotyledon moves out of the seed and becomes green; plants usually terrestrial. (subfamily Pitcairnioideae) |
3 |
| 2a. | Seed appendages finely divided and forming a coma, always present; fruit dehiscent; leaves always entire; indument almost always of obviously radially symmetric scales; on seed germination the cotyledon remains in the seed; plants mostly epiphytic. (subfamily Tillandsioideae) |
18 |
| 3. | Plants monoecious or, if rarely dioecious (Cottendorfia) or polygamodioecious (Dyckia maritima, D. selloa, and D. hebdingii), then the petals yellow or orange and plants native to northeastern and southernmost Brazil. | 4 |
| 3a. | Plants dioecious with functionally unisexual flowers; petals rose or white; plants of Texas, Mexico, and northern Central America. | Hechtia |
| 4. | Bases of the filaments separate from each other, but sometimes individually adnate to the petals and sepals | .5 |
| 4a. | Bases of the filaments forming a tube and adnate to the petals; petals yellow to orange; plants of Brazil, Uruguay, Paraguay, and Argentina. | Dyckia |
| 5. | Seeds obviously and persistently appendaged. | 6 |
| 5a. | Seeds not appendaged at maturity. | 16 |
| 6. | Petal blades tightly spiraled after anthesis, broad, distinct from the bottom portion; leaf blades narrowly triangular, never contracted at base; ovary superior or slightly inferior; Andean plants of open slopes and summits from Costa Rica and Guayana to Chile and Argentina. | Puya |
| 6a. | Petal blades remaining separate after anthesis or, if sometimes slightly spiraled (Deuterocohnia), then not distinct from the bottom portion. | 7 |
| 7. | Ovary wholly superior; petals regular. | 8 |
| 7a. | Ovary partially to wholly inferior, or, if superior then the petals zygomorphic (Pitcairnia spp.). | 14 |
| 8. | Petals naked or with paired appendages (Steyerbromelia). | 9 |
| 8a. | Petals each bearing a single basal appendage; xerophytic plants of the southern Andes from Peru to Chile, Argentina, and W. Brazil. | Deuterocohnia |
| 9. | Seeds with a sickle-like appendage; petal blades narrow, indistinct from the base; plants of NE Brazil. | Encholirium |
| 9a. | Seeds bicaudate-appendaged. | 10 |
| 10. | Anthers basifixed, linear, coiled at anthesis, inner filaments adnate to the base of the petals; leaf blades thin, more or less contracted at base; mesophytic plants of Mexico to Argentina and W. Brazil. | Fosterella |
| 10a. | Anthers subbasifixed , stout, straight; filaments usually free; leaf blades firm, not contracted at base; plants of the Guayana Highlands | 11 |
| 11. | Stigma lobes uniform; sepals rolled-up lengthwise, each with its left side covering the right side of the next one. | 12 |
| 11a. | Stigma lobes distorted; sepals spiral in form with the abaxial overlapping both the adaxial, cells of leaf epidermis straight walled, plants of NE Brazil. | Cottendorfia |
| 12. | Petals naked; stigmas straight, erect; flowers mostly pedicellate. | 13 |
| 12a. | Petals with paired appendages; stigmas broad, strongly contorted; flowers sessile; inflorescence compound, lax. | Steyerbromelia |
| 13. | Flowers large, Floral bracts large and enveloping. | Connellia |
| 13a. | Flowers small, Floral bracts small. | Lindmania |
| 14. | Petals large, naked, or appendaged, usually zygomorphic and forming a hood over the anthers; sepals convolute with the left side of each overlapping the right of the next one; plants of Mexico and the West Indies to Argentina and Brazil. | Pitcairnia |
| 14a. | Petals minute, regular; sepals spiral in form with both adaxial ones overlapping the abaxial; plants of the Guayana Highlands. | 16 |
| 15. | Epigynous tube lacking; inflorescence open and definitely branched. | Brocchinia |
| 15a. | Epigynous tube well developed; inflorescence sessile, capitate. | Ayensua |
| 16. | Sepals convolute; petals zygomorphic (Pitcairnia aphelandriflora). | 14 |
| 16a. | Sepals cochlear with both adaxial ones overlapping the abaxial; petals regular; ovary superior (in most species) to nearly inferior; plants of the Guayana Highlands. | 17 |
| 17. | Petals naked; inflorescence scapose, pinnate, and more or less open or sessile and capitate. | Navia |
| 17a. | Petals with 2 appendages; inflorescence long-scapose, simple, densely cylindric. | Brewcaria |
| 18. | Ovary nearly or quite superior; seeds plumose on base or apex or largely on the base and only slightly on the apex. | 19 |
| 18a. | Ovary only half superior; seeds equally plumose-appendaged at both ends; flowers polystichous. Lesser Antilles, Trinidad, adjacent Venezuela. | Glomeropitcairnia |
| 19. | Appendage of the seed wholly or largely basal, straight at maturity. | 20 |
| 19a. | Appendage of the seed largely apical, folded at maturity; sepals strongly asymmetric in most species; flowers in at least slightly more than 2 ranks; leaves often cretaceous-coated on the inside. Florida, Mexico, and the West Indies to Brazil and Peru. | Catopsis |
| 20. | Petal bases free or with very short tube exceeded by the sepals; flowers distichous in most species. | 21 |
| 20a. | Petal bases conglutinated in a tube, equaling the sepals or, rarely, the petals entirely included in the sepals. | 25 |
| 21. | Petals naked; inflorescence of 1 or more distichous-flowered spikes or racemes or rarely reduced to 1 or more polystichous-flowered spikes or to a single flower; plants of southern United States to Argentina and Chile. | 24 |
| 21a. | Petal appendages on the inside of the petal base; Mexico and the West Indies to Argentina and Uruguay. | 22 |
| 22. | Seed with the apical appendage divided into a short coma; petals linear long, fusiform, usually 10-15 times longer than wide, soon flaccid and drooping. | Alcantarea |
| 22a. | Seed with the apical appendage minute and undivided; petals elliptical, usually 5-10 times longer than wide, usually firm and remaining more or less erect after anthesis. | 23 |
| 23. | Flowers with brilliant coloration in most species, bright yellow, orange, or red, rarely dull to white, light yellow, or light orange; the adaxial petal pair arranged apically in respect to the abaxial; petal appendages tongue-shaped; stigma with the convolute blade type morphology, that is, 3 obviously spreading lobes covered with papillae. | Vriesea |
| 23a. | Flowers generally dull in color, white, greenish white, light green yellowish green, yellow, or light orange; the adaxial petal pair arranged basally in respect to the abaxial; petal appendages finger-like with 1-5 fingers of varying length; stigma with the cupulate type morphology, that is, 3 apical, capitate, cup-shaped lobes, without papillae. | Werauhia |
| 24. | Sepals symmetric or if slightly asymmetric, then ovate or lanceolate and broadest below the middle, free or variously connate; seeds usually with a distinct apical appendage. | Tillandsia |
| 24a. | Sepals asymmetric, free or nearly so, broadest near apex, not over 12mm long; seeds without apical appendage. | Racinaea |
| 25. | Petal bases always naked; spikes always polystichous-flowered. Florida, Mexico, and the West Indies to Brazil and Bolivia. | Guzmania |
| 25a. | Petal bases bearing appendages on the inside; flowers polystichous rarely secund or distichous. Colombia to Peru. | Mezobromelia |
| 26. | Sepals symmetric or nearly so. | 27 |
| 26a. | Sepals asymmetric. | 51 |
| 27. | Filaments forming a tube to which the fleshy petals are joined along their centers but with their margins free; sepals mostly free or nearly so; leaves very laxly and coarsely spinose-serrate. | 28 |
| 27a. | Filaments not connate but sometimes adnate. | 30 |
| 28. | Sepals with soft, usually broad apices; inflorescences compound. Mexico and the West Indies to Argentina and Uruguay. | Bromelia |
| 28a. | Sepals spinose-mucronate. | 29 |
| 29. | Inflorescence simple, with almost no scape. Argentina. | Deinacanthon |
| 29a. | Inflorescence branched with terminal cone-like branches, with a scape. S Mexico, Guatemala. | Hohenbergiopsis |
| 30. | Terminal axes of the inflorescence visible. | 31 |
| 30a. | Terminal axes of the inflorescence covered by leaves or bracts. | 37 |
| 31. | Petals naked; sepals 0.5-7 mm long. | 32 |
| 31a. | Petals appendaged; sepals mostly much larger. | 33 |
| 32. | Inflorescence compound; sepals broadly ovate or oblong, 0.5-2mm long. Costa Rica and Trinidad to Amazonian Brazil. | Araeococcus |
| 32a. | Inflorescence simple; sepals narrowly elliptic, 7mm long; flowers subsessile or pedicellate. Mount Itatiaia area in E Brazil. | Fernseea |
| 33. | Petals zygomorphic or tightly recoiled and flowers sessile. W Mexico and Central America to Argentina and Uruguay. | 34 |
| 33a. | Petals not zygomorphic. | 35 |
| 34. | Epigynous tube usually well developed. | Billbergia |
| 34a. | Epigynous tube shallow. W Mexico. | Ursulaea |
| 35. | Petals erect. E Brazil. | 36 |
| 35a. | Petals recoiled at the top. | Ursulaea |
| 36. | Flowers sessile. | Quesnelia |
| 36a. | Flowers pedicellate. | Neoglaziovia |
| 37. | Inflorescence simple, cone-like; flowers solitary in the axil of each bract. | 38 |
| 37a. | Inflorescence compound. | 45 |
| 38. | Scape short or none; cone-like branches nidular or axillary. | 39 |
| 38a. | Scape well developed, obvious. | 43 |
| 39. | Floral bracts leaf-like. NE Brazil. | Orthophytum |
| 39a. | Floral bracts bract-like. | 40 |
| 40. | Scape distinct, its bracts shorter than the floral bracts; petals naked. Mexico and Venezuela to Chile. | Greigia |
| 40a. | Scape none or very short. | 41 |
| 41. | Epigynous tube shallow, bowl-shaped (A. pitcairnioides) Brazil: Bahia. | Acanthostachys |
| 41a. | Epigynous tube cylindric, deep. Chile. | 42 |
| 42. | Sepals obtuse, stamens included, petals blue. | Fascicularia |
| 42a. | Sepals acute with pungent apex, stamens exserted, petals rose. | Ochagavia |
| 43. | Scape erect, without bracts (A. strobilacea). S Brazil, Paraguay, Argentina | .Acanthostachys |
| 43a. | Scape covered with bracts. | 44 |
| 44. | Scape bracts leaf-like, scape erect. NE Brazil. | Orthophytum |
| 44a. | Scape bracts bract-like; scape prostrate. French Guiana and adjacent Brazil. | Disteganthus |
| 45. | Inflorescence obviously compound with several strobils on an elongate floral axis. | 46 |
| 45a. | Inflorescence pseudosimple with hands or flat fascicles in the axils of large bracts. | 47 |
| 46. | Floral bracts leaf-like, serrulate; cone-like branches sessile or subsessile. NE Brazil. | Orthophytum |
| 46a. | Floral bracts bract-like, entire; cone-like branches on distinct scapes. Mexico and Venezuela to Chile. | Greigia |
| 47. | Outer bracts of the inflorescence leaf-like; sepals high connate; petals naked. NE Brazil. | Cryptanthus |
| 47a. | Outer bracts of the inflorescence bract-like, large, and covering most of the flowers. E Brazil. | 48 |
| 48. | Petals erect and apex distinctly obtuse cucullate, connate or agglutinated in a tube the height of the sepals. | Nidularium |
| 48a. | Petals sub-erect to spreading at anthesis, free or nearly so. | 49 |
| 49. | Inflorescence wool persistent after anthesis. | Edmundoa |
| 49a. | Inflorescence wool not persistent. | 50 |
| 50. | Stolons slender, flowers 20 35 mm long. | Canistropsis |
| 50a. | Stolons stout or none, flowers 45 - 80 mm long. | Wittrockia |
| 51. | Ovaries coalescing to form a compound fruit; inflorescence simple, strobilate. | 52 |
| 51a. | Ovaries always remaining distinct. | 53 |
| 52. | Inflorescence with a small, inconspicuous coma, never producing basal shoots; plant propagating by elongate rhizomes; petals bearing vertical folds. Paraguay and adjacent areas. | Pseudananas |
| 52a. | Inflorescence usually with a large conspicuous coma (lacking in A. monstrosus), often with basal shoots; rhizomes lacking; petals usually bearing well-developed scales. Probably native from Paraguay to the Amazon Basin, now pantropical. | Ananas |
| 53. | Flowers pedicellate. | 54 |
| 53a. | Flowers sessile or subsessile. | 59 |
| 54. | Inflorescence nidular, simple in most species; petals naked. Amazonia, E Brazil. | Neoregelia |
| 54a. | Inflorescence scapose. | 55 |
| 55. | Sepals more or less connate, long-mucronate; petals appendaged. E Brazil. | Portea |
| 55a. | Sepals free or unarmed. | 56 |
| 56. | Inflorescence simple; sepals without sharp tip. | 57 |
| 56a. | Inflorescence compound. | 58 |
| 57. | Petals naked. Colombia. | Pseudaechmea |
| 57a. | Petals appendaged. Colombia and Guyana to NE Brazil. | Aechmea subg. 2. Lamprococcus |
| 58. | Sepals 1.5-3 mm long; inflorescence glabrous; petals naked. Colombia to Suriname and Amazonian Brazil. | Araeococcus |
| 58a. | Sepals 3.5-22 mm long; inflorescence lepidote; petals appendaged. Mexico to Peru. | Aechmea subg. 1. Podaechmea |
| 59. | Petals appendaged with well-developed appendages. | 60 |
| 59a. | Petals naked or with lateral folds or rudimentary or reduced appendages. | 66 |
| 60. | Epigynous tube shallow or lacking; flowers in tubular cone-like branches; inflorescence mostly pinnate and lax, rarely digitate or simple (H. littoralis). Antilles to Venezuela and Brazil. | Hohenbergia |
| 60a. | Epigynous tube well developed; inflorescence various. | 61 |
| 61. | Sepals without a sharp tip. | 62 |
| 61a. | Sepals with a sharp tip. | 61b |
| 61b. | Inflorescence not involucrate. N and S America. | Aechmea subg. 3. Aechmea subg. 4. Ortgiesia subg. 6. Pothuava |
| 61c. | Inflorescence involucrate with large upper scape bracts and primary bracts. S. America. | Canistrum |
| 62. | Floral bracts attached basally, not decurrent nor forming pouches; flowers polystichous. | 63 |
| 62a. | Floral bracts decurrent and forming pouches around the flowers; flowers often distichous. N and S America. | Aechmea subg. 5. Platyaechmea |
| 63. | Inflorescence compound. | 64 |
| 63a. | Inflorescence simple. | 65 |
| 64. | Leaves distichous; blades marked with spots or bands; floral bracts minute; ovules obtuse (Q. marmorata). Brazil: Espirito Santo to Sao Paulo. | Quesnelia |
| 64a. | Leaves polystichous or the blades concolorous; floral bracts large to lacking; ovules long-caudate. Colombia, Venezuela, Amazonian Brazil. | Aechmea subg.2. Lamprococcus |
| 65. | Ovules obtuse (no further distinction possible without keying by species). E Brazil. | Quesnelia |
| 65a. | Ovules apiculate to caudate. Central America to Brazil and Argentina. | Aechmea subg. 7. Macrochordion |
| 66. | Ovary deeply sulcate; inflorescence simple or compound. NE Brazil. | Lymania |
| 66a. | Ovary evenly rounded. | 67 |
| 67. | Inflorescence lax; axes visible. | 68 |
| 67a. | Inflorescence dense. | 71 |
| 68. | Inflorescence simple. Costa Rica to Peru. | Ronnbergia |
| 68a. | Inflorescence pinnately compound. | 69 |
| 69. | Flowers very small; sepals not over 3mm long; ovules few; epigynous tube none. Costa Rica, Venezuela, Trinidad, Tobago, Guyana to Amazonian Brazil. | Araeococcus |
| 69a. | Flowers small to large; sepals more than 3 mm long; epigynous tube distinct. | 70 |
| 70. | Branches elongate, many-flowered; flowers perfect; anthers unappendaged. E and Amazonian Brazil and adjacent areas. | Streptocalyx |
| 70a. | Branches short, digitately few-flowered; flowers functionally unisexual on different plants; anthers appendaged. Central America: Guatemala to Costa Rica. | Androlepis |
| 71. | Flowers 2 or more in the axil of each bract. | 72 |
| 71a. | Flower single in the axil of each bract. | 73 |
| 72. | Inflorescence involucrate; sepals only slightly asymmetric, not with sharp tip or mucronulate. E Brazil. | Nidularium |
| 72a. | Inflorescence cone-like; sepals strongly asymmetric, mucronate. E and Amazonian Brazil and adjacent areas. | Streptocalyx |
| 73. | Petals naked or with lateral folds; bracts papery or leathery; leaf blades often petiolate. Costa Rica to Peru. | Ronnbergia |
| 73a. | Petals bearing rudimentary or reduced appendages; bracts mostly thick and ligneous; leaf blades never petiolate; pollen sulcate. Mexico to Peru and Amazonian Brazil, E Brazil. | Chevaliera |