Plant Systematics and Evolution

, Volume 184, Issue 3–4, pp 175–193 | Cite as

The supraspecific taxonomy and evolution of the fern genusAzolla (Azollaceae)

  • Richard M. K. Saunders
  • Keith Fowler


The systematics of the aquatic fern genusAzollaLam. is revised at the supraspecific level. Published morphological data are reviewed, and cytological and cladistic analyses of the genus conducted, enabling a discussion of the putative evolutionary trends in the genus, and a revision of the current taxonomy. A phylogenetically more acceptable subgeneric and sectional classification is proposed, viz. subg.Azolla sect.Azolla (comprisingA. filiculoidesLam.,A. rubraR. Br.,A caroliniana auct. nonWilld.,A. microphylla auct. nonKaulf. andA. mexicanaPresl), subg.Azolla sect.Rhizosperma (Mey.)Mett. (comprisingA. pinnataR. Br.), and subg.Tetrasporocarpia subg. nov. (comprisingA. niloticaDecne. exMett.).

Key words

Pteridophytes Rhizosperma Tetrasporocarpia water ferns Chromosome number cladistics cytology morphology systematics 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Arnold, C. A., 1955: A TertiaryAzolla from British Columbia. — Contr. Univ. Mich. Mus. Paleontol.12: 37–45.Google Scholar
  2. Ashton, P. J., Walmsley, R. D., 1976: The aquatic fernAzolla and itsAnabaena symbiont. — Endeavour35: 39–43.Google Scholar
  3. Ashton, P. J., Walmsley, R. D., 1984: The taxonomy and distribution ofAzolla species in southern Africa. — Bot. J. Linn. Soc.89: 239–247.Google Scholar
  4. Baker, J. G., 1886: A synopsis of theRhizocarpeae. — J. Bot.25: 97–101.Google Scholar
  5. Baker, J. G., 1887:Azolla Lam. — InBaker, J. G.: Handbook of the fern-allies, pp. 137–138. — London: George Bell.Google Scholar
  6. Brown, R., 1810: Prodromus Florae Novae Hollandiae et Insulae Van-Dieman. — London: Johnson.Google Scholar
  7. Brown, R. W., 1934: The recognisable species of the Green River Flora. — U.S. Geol. Surv. Prof. Pap.185 C: 45–68.Google Scholar
  8. Bůžek, Č, Konzalová, M., Kvaček, Z., 1988:Azolla remains from the Lower Miocene of the North-Bohemian Basin, Czechoslovakia. — Tertiary Res.9: 117–132.Google Scholar
  9. Christensen, C., 1906: Index Filicum. — Copenhagen: Hagerup.Google Scholar
  10. Collinson, M. E., 1980: A new multiple-floatedAzolla from the Eocene of Britain with a brief review of the genus. — Palaeontology23: 213–229.Google Scholar
  11. Courtillot, V., Féraud, G., Maluski, H., Vandamme, D., Moreau, M. G., Besse, J., 1988: Deccan flood basalts and the Cretaceous/Tertiary boundary. — Nature (London)333: 843–846.Google Scholar
  12. Dijkstra, S. A., 1961: Some Palaeocene megaspores and other small fossils. — Mededel. Geol. Sticht., n.s.,13: 5–11.Google Scholar
  13. Dorofeev, P. I., 1959: New species ofAzolla Lam. in Tertiary flora of USSR. — Bot. Ž.44: 1756–1763.Google Scholar
  14. Dumortier, B. C. J., 1829: Analyse des familles des plantes. — Tournay.Google Scholar
  15. Duncan, R. A., Pyle, D. G., 1988: Rapid eruption of the Deccan flood basalts at the Cretaceous/Tertiary boundary. — Nature (London)333: 841–843.Google Scholar
  16. Dunham, D. G., 1986: Taxonomic re-evaluation and species recognition ofAzolla Lam., with particular reference to sectionAzolla. — Ph.D. thesis, C.N.A.A., Portsmouth Polytechnic, U.K.Google Scholar
  17. Dunham, D. G., Fowler, K., 1987: Taxonomy and species recognition inAzolla Lam. — In International Rice Research Institute, (Eds):Azolla Utilization, Proc. WorkshopAzolla Use, Fuzhou, Fujian, China, 31 March–5 April 1985, pp. 7–16. — Manila: International Rice Research Institute.Google Scholar
  18. Farris, J. S., 1988: Hennig 86 Reference, version 1.5. — Port Jefferson Station, New York: published by the author.Google Scholar
  19. Foster, C. B., Harris, W. K., 1981:Azolla capricornica sp. nov. first Tertiary record ofAzolla Lam. (Salviniaceae) in Australia. — Trans. Roy. Soc. South Australia105: 195–204.Google Scholar
  20. Fowler, K., 1975: Megaspores and massulae ofAzolla prisca from the Oligocene of the Isle of Wight. — Palaeontology18: 483–507.Google Scholar
  21. Fowler, K., 1981: Reproductive structures in fossil and extant species of the genusAzolla. — InFowler, K.: Aspects of palynology in the Palaeogene of the Hampshire Basin, Southern England, pp. 1–100. — Ph.D. thesis, C.N.A.A., Portsmouth Polytechnic, U.K.Google Scholar
  22. Hall, J. W., 1968: A new genus ofSalviniaceae and a new species ofAzolla from the late Cretaceous. — Amer. Fern J.58: 77–88.Google Scholar
  23. Hall, J. W., 1969a: A reappraisal of the megaspores of two Eocene species ofAzolla. — J. Palaeont.43: 528–531.Google Scholar
  24. Hall, J. W., 1969b: Studies on fossilAzolla: primitive types of megaspores and massulae from the Cretaceous. — Amer. J. Bot.56: 1173–1180.Google Scholar
  25. Hall, J. W., 1970: A new section ofAzolla. — Taxon19: 302–303.Google Scholar
  26. Hall, J. W., 1974: CretaceousSalviniaceae. — Ann. Missouri Bot. Gard.61: 354–367.Google Scholar
  27. Hall, J. W., 1975:Ariadnesporites andGlomerisporites in the late Cretaceous: ancestralSalviniaceae. — Amer. J. Bot.62: 359–369.Google Scholar
  28. Hall, J. W., Bergad, R. D., 1971: A critical study of three Cretaceous salviniaceous megaspores. — Micropaleontology17: 345–356.Google Scholar
  29. Hall, J. W., Swanson, N. P., 1968: Studies on fossilAzolla: Azolla montana, a Cretaceous megaspore with many small floats. — Amer. J. Bot.55: 1055–1061.Google Scholar
  30. Herzog, R., 1938: Geographische Verbreitung der GattungenSalvinia undAzolla. — Bot. Arch.39: 219–225.Google Scholar
  31. Hills, L. V., Gopal, B., 1967:Azolla primaeva and its phylogenetic significance. — Canad. J. Bot.45: 1179–1191.Google Scholar
  32. Hills, L. V., Weiner, N., 1965:Azolla geneseana new species, and revision ofAzolla primaeva. — Micropaleontology11: 255–261.Google Scholar
  33. Jain, R. K., 1971: Pre-Tertiary records ofSalviniaceae. — Amer. J. Bot.58: 487–496.Google Scholar
  34. Jain, R. K., Hall, J. W., 1969: A contribution to the early Tertiary fossil record of theSalviniaceae. — Amer. J. Bot.56: 527–539.Google Scholar
  35. Lamarck, J. B. A. P. M. de, 1783: Encyclopedia méthodique botanique. 1. — Paris: Panchonke.Google Scholar
  36. Lin, Y. X., 1980: A systematic study of the familyAzollaceae with reference to the extending utilisation of certain species in China. — Acta Phytotax. Sinica18: 450–456.Google Scholar
  37. Loyal, D. S., 1958: Cytology of two species ofSalviniaceae. — Curr. Sci.27: 357–358.Google Scholar
  38. Loyal, D. S., 1975: Chromosome size and structure in some heterosporous ferns with a bearing on evolutionary problems. — InKachroo, P., (Ed.): Advancing frontiers in cytogenetics, pp. 293–298. — Delhi: Hindustan.Google Scholar
  39. Loyal, D. S., Gollen, A. K., Ratra, R., 1982: Morphological and cytotaxonomic observations onAzolla pinnata. — Fern Gaz.12: 230–232.Google Scholar
  40. Lumpkin, T. A., Plucknett, D. L., 1980:Azolla: botany, physiology and use as a green manure. — Econ. Bot.34: 111–153.Google Scholar
  41. Lumpkin, T. A., Plucknett, D. L., 1982:Azolla as a green manure: use and management in crop production. — Westview Tropical Agricult. Ser. No. 5. — Boulder, Colorado: Westview Press.Google Scholar
  42. Mahabalé, T. S., 1963: Evolutionary tendencies in the genusAzolla. — Mem. Indian Bot. Soc.4: 51–54.Google Scholar
  43. Martin, A. R. H., 1976a: Upper PalaeoceneSalviniaceae from the Woolwich/Reading beds near Cobham, Kent. — Palaeontology19: 173–184.Google Scholar
  44. Martin, A. R. H., 1976b: Some structures inAzolla megaspores, and an anomalous form. — Rev. Palaeobot. Palynol.21: 141–169.Google Scholar
  45. Melchoir, R. C., Hall, J. W., 1983: Some megaspores and other small fossils from the Wannagan Creek site (Paleocene), North Dakota. — Palynology7: 133–145.Google Scholar
  46. Mettenius, G. H., 1847: ÜberAzolla. — Linnaea20: 259–282.Google Scholar
  47. - 1867:Filicinae. — InKotschy, T., Peyritsch, J., (Eds): Plantae Tinneanae, pp. 51–54. — Wien.Google Scholar
  48. Meyen, F. J. F., 1836: Beiträge zur Kenntniss der Azollen. — Nova Acta Acad. Caesar. Leop. Carol.18(1: 505–524.Google Scholar
  49. Moore, A. W., 1969:Azolla: biology and agronomic significance. — Bot. Rev.35: 17–34.Google Scholar
  50. Nayak, S. K., Singh, P. K., 1989: Cytological studies in the genusAzolla. — Cytologia54: 275–286.Google Scholar
  51. Reid, E. M., Chandler, M. E. J., 1926: Catalogue of Cainozoic plants in the Department of Geology. 1. The Bembridge Flora. — London: British Museum (Natural History).Google Scholar
  52. Sadebeck, R., 1902:Salviniaceae. — InEngler, A., Prantl, K., (Eds): Die Natürlichen Pflanzenfamilien, 2nd edn. 1, pp. 383–402. — Leipzig: Engelmann.Google Scholar
  53. Sahni, B., 1941: Indian silicified plants. 1.Azolla intertrappea Sahni andH. S. Rao. — Proc. Indian Acad. Sci.B 14: 489–601.Google Scholar
  54. Sahni, B., Rao, H. S., 1943: A silicified flora from the Intertrappean cherts round Saugar in the Deccan. — Proc. Nat. Acad. Sci. IndiaB 13: 36–75.Google Scholar
  55. Saunders, R. M. K., 1990: The systematics of the aquatic fern genusAzolla Lam., with particular reference to sectionRhizosperma (Mey.)Mett. — Ph.D. thesis, C.N.A.A., Portsmouth Polytechnic, U.K.Google Scholar
  56. Saunders, R. M. K., Fowler, K., 1992: A morphological taxonomic revision ofAzolla Lam. sectionRhizosperma (Mey.)Mett. (Azollaceae). — Bot. J. Linn. Soc.109: 329–357.Google Scholar
  57. Schneller, J. J., 1990:Azollaceae. — InKramer, K. U., Green, P. S., (Eds): The families and genera of vascular plants. I. Pteridophytes and gymnosperms, pp. 57–60. — Berlin: Springer.Google Scholar
  58. Sculthorpe, C. D., 1967: The biology of aquatic vascular plants. — London: Edward Arnold.Google Scholar
  59. Shi, D.-J., Hall, D. O., 1988:Azolla and immobilized cyanobacteria (blue-green algae): from traditional agriculture to biotechnology. — Plants Today1: 5–12.Google Scholar
  60. Singh, P. K., Patra, R. N., Nayak, S. K., 1984: Sporocarp germination, cytology and mineral nutrition ofAzolla species. — InSilver, W. S., Schröder, E. C., (Eds): Practical applications ofAzolla for rice production. Proc. Intern. Workshop, Mayaguez, Puerto Rico, Nov. 17–19, 1982, pp. 55–65. — The Hague: Nijhoff Junk.Google Scholar
  61. Snead, R. J., 1969: Microfloral diagnosis of the Cretaceous-Tertiary boundary, Central Alberta. — Res. Council Alberta Bull.25: 1–148.Google Scholar
  62. Sporne, K. R., 1975: The morphology of Pteridophytes, 4th edn. — London: Hutchinson.Google Scholar
  63. Stergianou, K. K., Fowler, K., 1989: Preliminary report of chromosome counts in the genusAzolla (Pteridophyta). — Fern Gaz.13: 317–319.Google Scholar
  64. Stergianou, K. K., Fowler, K., 1990: Chromosome numbers and taxonomic implications in the fern genusAzolla (Azollaceae). — Pl. Syst. Evol.173: 223–239.Google Scholar
  65. Stough, J. B., 1968: New late Cretaceous palynomorphs from southern South America. — Univ. Kansas Paleontol. Contr.32: 1–7.Google Scholar
  66. Strasburger, E., 1873: ÜberAzolla. — Jena: Hermann Dabis.Google Scholar
  67. Svenson, H. K., 1944: The New World species ofAzolla. — Amer. Fern J.34: 69–84.Google Scholar
  68. Sweet, A. R., Chandrasekharam, A., 1973: Vegetative remains ofAzolla schopfii Dijkstra from Genesee, Alberta. — Canad. J. Bot.51: 1491–1496.Google Scholar
  69. Sweet, A. R., Hills, L. V., 1974: A detailed study of the genusAzollopsis. — Canad. J. Bot.52: 1625–1642.Google Scholar
  70. Sweet, A. R., Hills, L. V., 1976: Early Tertiary species ofAzolla subg.Azolla sect.Kremastospora from western and arctic Canada. — Canad. J. Bot.54: 334–351.Google Scholar
  71. Tan, B. C., Payawal, P., Watanabe, I., Lacdan, N., Ramirez, C., 1986: Modern taxonomy ofAzolla: a review. — Philipp. Agric.69: 491–512.Google Scholar
  72. Trivedi, B. S., Verma, C. L., 1971: Contributions to the knowledge ofAzolla indica sp. nov. from the Deccan Intertrappean Series M. P. India. — PalaeontographicaB 136: 71–82.Google Scholar
  73. Wagner, W. H., 1973: Some future challenges of fern systematics and phylogeny. — InJermy, A. C., Crabbe, J. A., Thomas, B. A., (Eds): The phylogeny and classification of the ferns. — Bot. J. Linn. Soc. (Suppl. 1)67: 245–256.Google Scholar
  74. Watanabe, I., Espinas, C. R., Berja, N. S., Alimagno, B. V., 1977: Utilization of theAzolla-Anabaena complex as a nitrogen fertilizer for rice. — Intern. Rice Res. Inst. Res. Pap. Ser.11: 1–15.Google Scholar
  75. Wettstein, R. von, 1903: Handbuch der Systematischen Botanik. 2. — Leipzig, Wien: Deuticke.Google Scholar

Copyright information

© Springer-Verlag 1993

Authors and Affiliations

  • Richard M. K. Saunders
    • 1
  • Keith Fowler
    • 1
  1. 1.School of Biological SciencesUniversity of PortsmouthPortsmouthU.K.

Personalised recommendations