Vol. 75 No. 1 (2020)

A Review of North American Isoetes engelmannii (Isoetaceae) complex hybrids, including the description of I. × fernaldii, hyb. nov. and I. × karenae, hyb. nov.

Daniel Francis Brunton
Beaty Centre for Species Discovery and Botany Section, Canadian Museum of Nature, Ottawa, Ontario K1P 6P4, Canada
Paul Clayton Sokoloff
Beaty Centre for Species Discovery and Botany Section, Canadian Museum of Nature, Ottawa, Ontario K1P 6P4, Canada
Published July 1, 2020
  • Isoetes,
  • hybrids,
  • Isoetes appalachiana,
  • Isoetes × brittonii,
  • Isoetes × bruntonii,
  • Isoetes × carltaylorii
  • ...More
How to Cite
Brunton, D. F., & Sokoloff, P. C. (2020). A Review of North American Isoetes engelmannii (Isoetaceae) complex hybrids, including the description of I. × fernaldii, hyb. nov. and I. × karenae, hyb. nov. Webbia, 75(1), 35-50. https://doi.org/10.36253/jopt-8355


The Isoetes engelmannii complex of eastern North America consists of 30 taxa including 13 named species. Nine of the 17 hybrids within the complex (the largest group of Isoetes hybrids in the world) have been formally described. Those named hybrids are reviewed here in light of recent additions to and enhancements of the morphological and cytological evidence employed in their original description. The pedigree of three of these, I. ×brittonii, I. ×bruntonii and I. ×carltaylorii, is updated and clarified. Formal descriptions are proposed for two additional taxa: I. ×fernaldii, hyb. nov. (I. engelmannii × I. hyemalis) and I. ×karenae, hyb. nov. (I. appalachiana × engelmannii). The potential for a further eight hybrid combinations to occur in the wild is also addressed.


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