The Botanical Review

, Volume 68, Issue 4, pp 474–487 | Cite as

Ornamentation ofIsoetes (Isoetaceae, Lycophyta) microspores

  • Lytton John Musselman


More than any other taxonomic character, megaspores have been used in the genusIsoetes (known by the English common name of “quillwort”), despite the fallacy of a single-character taxonomy. Microspores, on the other hand, have been largely neglected in taxonomic schemes. Like megaspores, terms for microspore ornamentation (also known as “sculpturing”) have not been standardized. I examined microspore ornamentation, including both macroornamentation and microornamentation, of 52 taxa from Africa, Asia, Australasia, Europe, North America, and South America with the scanning electron microscope. Macroornamentation is discernible with light microscopy; microornamentation requires scanning electron microscopy. Ornately sculptured spores were much more frequent than were laevigate or psilate patterns: 21 taxa had an echinate pattern; 19 had an aculeate pattern; 6 were cristate; 5 were psilate; and 1 was laevigate. The proximal and distal ridges and surfaces may vary in both the type and density of ornamentation. Distinct macroornamentation patterns characterize certain species groups. Microornamentation types include granulate, bacillate, fimbriate, and filamentose: of the microspores I examined, virtually all were partially granulate; 11 were bacillate; 4 were fimbriate; and 1 was filamentose. Based on this limited sampling, species with a higher ploidy level often have larger microspores, but no clear relationship between microspore ornamentation and ploidy level was established, nor were any geographical or ecological trends clear. Like megaspores, microspore ornamentation is strongly convergent. Although microspores are often attached to megaspores, the role of spore ornamentation in coordinated dispersal remains unclear.


Botanical Review Ploidy Level Distal Surface Proximal Surface Spore Surface 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

Literature Cited

  1. Hickey, R. J. 1986.Isoëtes megaspore surface morphology: Nomenclature, variation, and systematic importance. Amer. Fern J. 76(1): 1–16.CrossRefGoogle Scholar
  2. Lellinger, D. B. &W. C. Taylor. 1997. A classification of spore ornamentation in the Pteridophyta. Pp. 33–412in R. J. Johns (ed.), Holttum: Memorial Volume. Royal Botanic Gardens, Kew.Google Scholar
  3. Lugardon, B. 1976. Sur la structure fine de l’exospore dans les divers groupes de Pteridophytes actuelles (microspores et isospores). Pp. 231–250in I. K. Ferguson and J. Muller (eds.), The evolutionary significance of the exine. Linnean Society Symposium Series, 1. Academic Press, London.Google Scholar
  4. Pfeiffer, N. E. 1922. Monograph of the Isoetaceae. Ann. Missouri Bot. Gard. 9: 79–233.CrossRefGoogle Scholar
  5. Taylor, W. C., N. T. Luebke, D. M. Britton, R. J. Hickey &D. F. Brunton. 1993. Isoetaceae Reichenbach Quillwort family. Pp. 64–75in Flora of North America north of Mexico, 2: Pteridophytes and gymnosperms. Oxford Univ. Press, New York.Google Scholar
  6. Tryon, A. F. &B. Lugardon. 1991. Spores of the Pteridophyta: Surface, wall structure, and diversity based on electron microscope studies. Springer-Verlag, New York.Google Scholar
  7. Uehara, K., S. Kurita, N. Sahashi &T. Ohmoto. 1991. Ultrastructural study on microspore wall morphogenesis inIsoetes japonica (Isoetaceae). Amer. J. Botany 78(9): 1182–1190.CrossRefGoogle Scholar

Copyright information

© The New York Botanical Garden 2003

Authors and Affiliations

  • Lytton John Musselman
    • 1
  1. 1.Department of Biological SciencesOld Dominion UniversityNorfolkUSA

Personalised recommendations