Articles
A Review of North American Isoetes engelmannii (Isoetaceae) complex hybrids, including the description of I. × fernaldii, hyb. nov. and I. × karenae, hyb. nov.
Paul Clayton Sokoloff
Published 2020-07-01
Keywords
- 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
Abstract
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.
References
Britton, DM. 1991. A hybrid Isoetes, I. ×harveyi, in northeastern North America. Canad. J. Botany 69: 634-640. https://doi.org/10.1139/b91-085
Britton, DM and Brunton, DF. 1989. A New Isoetes Hybrid (Isoetes echinospora x riparia) for Canada. Can. J. Bot. 67: 2995-3002. https://doi.org/10.1139/b92-059
Britton, DM and Brunton, DF. 1996. Isoetes ×pseudotruncata, a new triploid hybrid from western Canada and Alaska. Can. J. Bot. 74: 51-59 https://doi.org/10.1139/b96-008
Britton, DM, Catling, PM, Norris, J and Varga, S. 1991. Engelmann’s Quillwort, Isoetes engelmannii, an addition to the aquatic flora of Canada. Canad. Field-Nat. 105:67-70. https://www.biodiversitylibrary.org/item/106992#page/75/mode/1up
Brunton, DF. 2015. Key to the Quillworts (Isoetes: Isoetaceae) of the Southeastern United States. Amer. Fern J. 105: 86-100. https://doi.org/10.1640/amfj-105-02-86-100.1
Brunton, DF. 2018 [2019]. Distribution and taxonomy of Isoetes tuckermanii ssp. acadiensis, comb. nov. (Isoetaceae) in North America. Canadian Field-Naturalist 132: 360-367. http://doi.org/10.22621/cfn.v132i4.2084
Brunton, DF and Britton, DM. 1996. Taxonomy and Distribution of Isoetes valida (Isoetaceae). Amer. Fern J. 86: 16-25. https://doi.org/10.2307/1547604
Brunton, DF and Britton, DM. 1997. Appalachian Quillwort, (Isoetes appalachiana, sp. nov.; Isoetaceae), a new pteridophyte from the eastern United States. Rhodora 99: 118-133. https://biodiversitylibrary.org/page/33310811
Brunton, DF and Britton, DM. 1999. Isoetes ×echtuckerii, hyb. nov., a new triploid quillwort from northeastern North America. Canad J. Bot. 77: 1662-1668. https://doi.org/10.1139/cjb-77-11-1662
Brunton, DF and Britton, DM. 2006. Isoetes ×novae-angliae, a new quillwort (Isoetaceae) from northeastern North America. Rhodora 108: 228-241. https://doi.org/10.3119/0035-4902(2006)108[228:INIAAH]2.0.CO;2
Brunton, DF, Britton, DM and Taylor, WC. 1994. Isoetes hyemalis, sp. nov. (Isoetaceae); a new quillwort from the southeastern United States. Castanea 59 (1): 12-21.
Brunton, DF and McNeill, J. 2015 Status, Distribution and Nomenclature of the Northern Quillwort, Isoetes septentrionalis, sp. nov. (Isoetaceae), in Canada. Canad. Field-Nat. 129: 174-180. https://doi.org/10.22621/cfn.v129i2.1698
Brunton, DF and Sokoloff, PC. 2018. Isoetes ×robusta, comb. nov., the appropriate name for I. echinospora x septentrionalis (Isoetaceae). Rhodora 120 (998): 300-309. https://doi.org/10.3119/18-01
Brunton, DF and Taylor, WC. 1990. Isoëtes ×brittonii hyb. nov. (Isoëtaceae): A Naturally Occurring Hybrid (I. engelmannii x I. riparia) in the Eastern United States. Amer. Fern J. 80: 82-89. https://doi.org/10.2307/1547173
Brunton, DF and Troia, A. 2018. Global review of recent taxonomic research into Isoetes (Isoetaceae), with implications for biogeography and conservation. Fern Gaz. 20 (Part 8): 309-333.
Cody, WJ and Britton, DM. 1989. The Ferns and Fern Allies of Canada. Research Branch Publication 1829E, Agriculture Canada, Ottawa. https://doi.org/10.5962/bhl.title.53784
Dodge, R. 1897. A New Quillwort. Bot. Gaz. 23: 32-39. https://doi.org/10.1086/327458
Eaton, AA. 1898. I. foveolata A. A. Eaton, n. sp., pg. 38-39 in R. Dodge, R., Ferns and Fern Allies of New England. W. N. Clute & Co., Binghamton.
Eaton, AA. 1900. The genus Isoetes in New England, In: Fernwort Papers, pp. 1-16. N. Clute & Co., Binghamton.
Gianguzzi L, D’Amico, A and Troia A. 2017. Notes on the distribution, ecology and conservation status of two very rare sedges (Carex, Cyperaceae) rediscovered in Sicily (Italy). Botany Letters 164: 339-349. https://doi.org/10.1080/23818107.2017.1363659
Goulet BE, Roda, F and Hopkins R. 2017. Hybridization in Plants: Old Ideas, New Techniques. Plant Physiology 173: 65-78. https://doi.org/10.1104/pp.16.01340
Heafner, KD and Bray, RD. 2005. Taxonomic Reassessment of North American Granite Outcrop Isoetes Species with Emphasis on Vegetative Morphology and I. piedmontana (Pfeiffer) Reed sensu lato. Castanea 70: 204–221. https://doi.org/10.2179/04-29.1
Hickey, RJ, Taylor, WC and Luebke, NT. 1989. The Species Concept in Pteridophyta with Special Reference to Isoëtes. Amer. Fern J. 79: 78-89. https://doi.org/10.2307/1547162
Hoot, S, Napier, BNS and Taylor, WC. 2004. Revealing Unknown or Extinct Lineages with Isoetes (Isoetaceae) using DNA Sequences from Hybrids. Amer. J. Bot. 91: 899-904. https://doi.org/10.3732/ajb.91.6.899
Hugo, NR and Ware, DME. 2012. Plant Discovery and Documentation in Virginia: A Historical Perspective, pp. 6-23, In: Weakley, A. Ludwig, JC and Townsend, JF. Flora of Virginia. Botanical Research Institute of Texas, Fort Worth. 1554 pp.
Jeffrey, EC. 1937. The cytology of a heterosporous Isoetes. Bot. Mag. (Tokyo) 521: 203-209. https://doi.org/10.15281/jplantres1887.51.203
Kott, LS and Bobbette, RSW. 1980. Isoëtes eatonii, a Quillwort New for Canada. Canad. Field-Nat. 94: 163-166. https://www.biodiversitylibrary.org/item/89247#page/179/mode/1up
Larsen, E. and Rydin, C. 2016. Disentangling the Phylogeny of Isoetes (Isoetales) Using Nuclear and Plastic Data. International Journal of Plant Sciences 177: 157-164. http://doi.org/10.1086/684179.
Luebke, NT. 1992. Three New Species of Isöetes for the Southeastern United States. Amer. Fern J. 82: 23-26. https://doi.org/10.2307/1547757
Matthews, J. F. and W. M. Murdy. 1969. A study of Isoetes common to the granite outcrops of the southeastern Piedmont, United States. Bot. Gaz. 130: 53-61. https://doi.org/10.1086/336469
McVaugh, R. 1943. The Vegetation of the Granitic Flat-Rocks of the Southeastern United States. Ecological Monographs 13: 119-166. https://doi.org/10.2307/1943526
Mochalova, OA, Bobrov, AA and Brunton, DF. 2015. Isoëtes in Kamchatka (northern Russian Far East), with Description of a New Hybrid I. ×paratunica (I. asiatica x I. maritima). Amer. Fern J. 105:101-112. https://doi.org/10.1640/amfj-105-02-101-112.1
Montgomery, JD and Taylor, WC. 1994. Confirmation of a Hybrid Isoetes from New Jersey. Amer. Fern J. 84: 115-120. https://doi.org/10.2307/1547707
Musselman, LJ, Bray, RD and Knepper, DA. 1996. Isoetes × bruntonii (Isoetes engelmannii x I. hyemalis), A New Hybrid Quillwort from Virginia. Amer. Fern J. 86: 8-15. https://doi.org/10.2307/1547603
Musselman, LJ, Bray, RD and Knepper, DA. 1997. Isoetes ×carltaylorii (Isoetes acadiensis x Isoetes engelmannii), a new interspecific quillwort hybrid from the Chesapeake Bay. Can. J. Bot. 875: 301-309. https://doi.org/10.1139/b97-032
Musselman, LJ and Knepper, DA. 1994. Quillworts of Virginia. Amer. Fern J. 84: 48-68. https://doi.org/10.2307/1547699
Musselman, LJ, Knepper, DA, Bray, RD, Caplen, A and Ballou, C. 1995. A new Isoetes Hybrid from Virginia. Castanea 60:245–254.
Palmer, D. 2018. Michigan Ferns & Lycophytes. University of Michigan Press, Ann Arbor. pp. 381.
Pease, AS. 1951. Merritt Lyndon Fernald 1873 – 1950. Rhodora 53: 33-39.
Plume O, Raimondo FM and Troia A. 2015. Hybridization and competition between the endangered sea marigold (Calendula maritima, Asteraceae) and a more common congener. Pl. Biosyst. 149: 68-77, https://doi.org/10.1080/11263504.2013.810182
Proctor, GR. 1949. Isoetes riparia and its variants. Amer. Fern J. 39: 110-121. https://doi.org/10.2307/1545830
Schafran, PW. 2019. Molecular systematics of Isoëtes (Isoëtaceae) in eastern North America. PhD Thesis, Old Dominion University, Norfolk, Virginia.
Schafran, PW, Zimmer, E, Taylor, WC and Musselman, LJ. 2018. A Whole Chloroplast Genome Phylogeny of Diploid Species of Isoetes (Isoetaceae, Lycopodiophyta) in the Southeastern United States. Castanea 83(2): 224–235. https://doi.org/10.2179/17-132
Sigel, EM, Der, JP, Windham, MD and Pryer, KM. 2019. Expression Level Dominance and Homeolog Expression Bias in Recurrent Origins of the Allopolyploid Fern Polypodium hesperium. Amer. Fern J. 109: 224-247. https://doi.org/10.1640/0002-8444-109.3.224
Singh, SK, Shukla, SK, Dubey, NK and Shukla, PK. 2018. Isoetes ×gopalkrishnae (Isoetaceae), a new interspecific hybrid from central India. Phytotaxa 362: 68-76. https://doi.org/10.11646/phytotaxa.362.1.5
Takamiya, M. 1999. Natural history and taxonomy of Isoetes (Isoetaceae). Acta Phytotax. Geobot. 50: 101-138.
Takamiya, M, Watanabe, M and Ono, K. 1997. Biosystematic Studies on the Genus Isoetes in Japan IV. Morphology and Anatomy of Sporophytes, Phytogeography and Taxonomy. Acta Phytotax. Geobot. 48: 89-122.
Taylor, WC and Luebke, NT. 1988. Isoetes ×hickeyi: A Naturally Occurring Hybrid between I. echinospora and I. macrospora. Amer. Fern J. 78: 6-13. https://doi.org/10.2307/1547597
Taylor, WC, Luebke, NT and Smith, MB. 1985. Speciation and Hybridization in the North American Quillworts. Proceedings of the Royal Society of Edinburgh Section B (Biological Sciences) 86: 259-263. https://doi.org/10.1017/S0269727000008216
Taylor, WC, Luebke, NT, Britton, DM, Hickey, RJ and Brunton, DF. 1993. Isoetaceae. pp. 64-75 In, FNA Editorial Committee (eds.), Flora of North America north of Mexico, Volume 2. Oxford University Press, New York. pp. 475.0
Taylor, WC, Moran, RC and Brunton, DF. 2016. Isoëtaceae, the Quillwort Family. R.F.C. Naczi, J. R. Abbott, and Collaborators, New Manual of Vascular Plants of Northeastern United States and Adjacent Canada, online edition of 2016. NYBG Press, New York [published Online: 29 April 2016]. https://doi.org/10.21135/893275471.015
Thiers, B. [continuously updated]. Index Herbariorum: A global directory of public herbaria and associated staff. New York Botanical Garden's Virtual Herbarium. Available from http://sweetgum.nybg.org/science/ih/.
Troia, A and Greuter, W. 2014. A critical conspectus of Italian Isoetes (Isoetaceae). Pl. Biosyst. 148: 13-20. https://doi.org/10.1080/11263504.2013.878409
Troia, A, Pereira, JB, Kim, C and Taylor, WC. 2016. The genus Isoetes (Isoetaceae): a provisional checklist of the accepted and unresolved taxa. Phytotaxa 277: 101-145. http://dx.doi.org/10.11646/phytotaxa.277.2.1
Tryon, AF and Moran, RC. 1997. The Ferns and Allied Plants of New England. Massachusetts Audubon Society, Lincoln.
Weldy, T, Werier, D and Nelson, A. 2019. New York Flora Atlas. http://newyork.plantatlas.usf. edu [accessed 20 November 2019]
Wood, D, Besnard, G, Beerling, DJ, Osborne, CP and Christin, P-A. 2019. Phylogenomics supports a Cenozoic rediversification of the “living fossil” Isoetes. BioRxiv (Dec 2019) 1-37. https://doi.org/10.1101/2019.12.23.886994.
Britton, DM and Brunton, DF. 1989. A New Isoetes Hybrid (Isoetes echinospora x riparia) for Canada. Can. J. Bot. 67: 2995-3002. https://doi.org/10.1139/b92-059
Britton, DM and Brunton, DF. 1996. Isoetes ×pseudotruncata, a new triploid hybrid from western Canada and Alaska. Can. J. Bot. 74: 51-59 https://doi.org/10.1139/b96-008
Britton, DM, Catling, PM, Norris, J and Varga, S. 1991. Engelmann’s Quillwort, Isoetes engelmannii, an addition to the aquatic flora of Canada. Canad. Field-Nat. 105:67-70. https://www.biodiversitylibrary.org/item/106992#page/75/mode/1up
Brunton, DF. 2015. Key to the Quillworts (Isoetes: Isoetaceae) of the Southeastern United States. Amer. Fern J. 105: 86-100. https://doi.org/10.1640/amfj-105-02-86-100.1
Brunton, DF. 2018 [2019]. Distribution and taxonomy of Isoetes tuckermanii ssp. acadiensis, comb. nov. (Isoetaceae) in North America. Canadian Field-Naturalist 132: 360-367. http://doi.org/10.22621/cfn.v132i4.2084
Brunton, DF and Britton, DM. 1996. Taxonomy and Distribution of Isoetes valida (Isoetaceae). Amer. Fern J. 86: 16-25. https://doi.org/10.2307/1547604
Brunton, DF and Britton, DM. 1997. Appalachian Quillwort, (Isoetes appalachiana, sp. nov.; Isoetaceae), a new pteridophyte from the eastern United States. Rhodora 99: 118-133. https://biodiversitylibrary.org/page/33310811
Brunton, DF and Britton, DM. 1999. Isoetes ×echtuckerii, hyb. nov., a new triploid quillwort from northeastern North America. Canad J. Bot. 77: 1662-1668. https://doi.org/10.1139/cjb-77-11-1662
Brunton, DF and Britton, DM. 2006. Isoetes ×novae-angliae, a new quillwort (Isoetaceae) from northeastern North America. Rhodora 108: 228-241. https://doi.org/10.3119/0035-4902(2006)108[228:INIAAH]2.0.CO;2
Brunton, DF, Britton, DM and Taylor, WC. 1994. Isoetes hyemalis, sp. nov. (Isoetaceae); a new quillwort from the southeastern United States. Castanea 59 (1): 12-21.
Brunton, DF and McNeill, J. 2015 Status, Distribution and Nomenclature of the Northern Quillwort, Isoetes septentrionalis, sp. nov. (Isoetaceae), in Canada. Canad. Field-Nat. 129: 174-180. https://doi.org/10.22621/cfn.v129i2.1698
Brunton, DF and Sokoloff, PC. 2018. Isoetes ×robusta, comb. nov., the appropriate name for I. echinospora x septentrionalis (Isoetaceae). Rhodora 120 (998): 300-309. https://doi.org/10.3119/18-01
Brunton, DF and Taylor, WC. 1990. Isoëtes ×brittonii hyb. nov. (Isoëtaceae): A Naturally Occurring Hybrid (I. engelmannii x I. riparia) in the Eastern United States. Amer. Fern J. 80: 82-89. https://doi.org/10.2307/1547173
Brunton, DF and Troia, A. 2018. Global review of recent taxonomic research into Isoetes (Isoetaceae), with implications for biogeography and conservation. Fern Gaz. 20 (Part 8): 309-333.
Cody, WJ and Britton, DM. 1989. The Ferns and Fern Allies of Canada. Research Branch Publication 1829E, Agriculture Canada, Ottawa. https://doi.org/10.5962/bhl.title.53784
Dodge, R. 1897. A New Quillwort. Bot. Gaz. 23: 32-39. https://doi.org/10.1086/327458
Eaton, AA. 1898. I. foveolata A. A. Eaton, n. sp., pg. 38-39 in R. Dodge, R., Ferns and Fern Allies of New England. W. N. Clute & Co., Binghamton.
Eaton, AA. 1900. The genus Isoetes in New England, In: Fernwort Papers, pp. 1-16. N. Clute & Co., Binghamton.
Gianguzzi L, D’Amico, A and Troia A. 2017. Notes on the distribution, ecology and conservation status of two very rare sedges (Carex, Cyperaceae) rediscovered in Sicily (Italy). Botany Letters 164: 339-349. https://doi.org/10.1080/23818107.2017.1363659
Goulet BE, Roda, F and Hopkins R. 2017. Hybridization in Plants: Old Ideas, New Techniques. Plant Physiology 173: 65-78. https://doi.org/10.1104/pp.16.01340
Heafner, KD and Bray, RD. 2005. Taxonomic Reassessment of North American Granite Outcrop Isoetes Species with Emphasis on Vegetative Morphology and I. piedmontana (Pfeiffer) Reed sensu lato. Castanea 70: 204–221. https://doi.org/10.2179/04-29.1
Hickey, RJ, Taylor, WC and Luebke, NT. 1989. The Species Concept in Pteridophyta with Special Reference to Isoëtes. Amer. Fern J. 79: 78-89. https://doi.org/10.2307/1547162
Hoot, S, Napier, BNS and Taylor, WC. 2004. Revealing Unknown or Extinct Lineages with Isoetes (Isoetaceae) using DNA Sequences from Hybrids. Amer. J. Bot. 91: 899-904. https://doi.org/10.3732/ajb.91.6.899
Hugo, NR and Ware, DME. 2012. Plant Discovery and Documentation in Virginia: A Historical Perspective, pp. 6-23, In: Weakley, A. Ludwig, JC and Townsend, JF. Flora of Virginia. Botanical Research Institute of Texas, Fort Worth. 1554 pp.
Jeffrey, EC. 1937. The cytology of a heterosporous Isoetes. Bot. Mag. (Tokyo) 521: 203-209. https://doi.org/10.15281/jplantres1887.51.203
Kott, LS and Bobbette, RSW. 1980. Isoëtes eatonii, a Quillwort New for Canada. Canad. Field-Nat. 94: 163-166. https://www.biodiversitylibrary.org/item/89247#page/179/mode/1up
Larsen, E. and Rydin, C. 2016. Disentangling the Phylogeny of Isoetes (Isoetales) Using Nuclear and Plastic Data. International Journal of Plant Sciences 177: 157-164. http://doi.org/10.1086/684179.
Luebke, NT. 1992. Three New Species of Isöetes for the Southeastern United States. Amer. Fern J. 82: 23-26. https://doi.org/10.2307/1547757
Matthews, J. F. and W. M. Murdy. 1969. A study of Isoetes common to the granite outcrops of the southeastern Piedmont, United States. Bot. Gaz. 130: 53-61. https://doi.org/10.1086/336469
McVaugh, R. 1943. The Vegetation of the Granitic Flat-Rocks of the Southeastern United States. Ecological Monographs 13: 119-166. https://doi.org/10.2307/1943526
Mochalova, OA, Bobrov, AA and Brunton, DF. 2015. Isoëtes in Kamchatka (northern Russian Far East), with Description of a New Hybrid I. ×paratunica (I. asiatica x I. maritima). Amer. Fern J. 105:101-112. https://doi.org/10.1640/amfj-105-02-101-112.1
Montgomery, JD and Taylor, WC. 1994. Confirmation of a Hybrid Isoetes from New Jersey. Amer. Fern J. 84: 115-120. https://doi.org/10.2307/1547707
Musselman, LJ, Bray, RD and Knepper, DA. 1996. Isoetes × bruntonii (Isoetes engelmannii x I. hyemalis), A New Hybrid Quillwort from Virginia. Amer. Fern J. 86: 8-15. https://doi.org/10.2307/1547603
Musselman, LJ, Bray, RD and Knepper, DA. 1997. Isoetes ×carltaylorii (Isoetes acadiensis x Isoetes engelmannii), a new interspecific quillwort hybrid from the Chesapeake Bay. Can. J. Bot. 875: 301-309. https://doi.org/10.1139/b97-032
Musselman, LJ and Knepper, DA. 1994. Quillworts of Virginia. Amer. Fern J. 84: 48-68. https://doi.org/10.2307/1547699
Musselman, LJ, Knepper, DA, Bray, RD, Caplen, A and Ballou, C. 1995. A new Isoetes Hybrid from Virginia. Castanea 60:245–254.
Palmer, D. 2018. Michigan Ferns & Lycophytes. University of Michigan Press, Ann Arbor. pp. 381.
Pease, AS. 1951. Merritt Lyndon Fernald 1873 – 1950. Rhodora 53: 33-39.
Plume O, Raimondo FM and Troia A. 2015. Hybridization and competition between the endangered sea marigold (Calendula maritima, Asteraceae) and a more common congener. Pl. Biosyst. 149: 68-77, https://doi.org/10.1080/11263504.2013.810182
Proctor, GR. 1949. Isoetes riparia and its variants. Amer. Fern J. 39: 110-121. https://doi.org/10.2307/1545830
Schafran, PW. 2019. Molecular systematics of Isoëtes (Isoëtaceae) in eastern North America. PhD Thesis, Old Dominion University, Norfolk, Virginia.
Schafran, PW, Zimmer, E, Taylor, WC and Musselman, LJ. 2018. A Whole Chloroplast Genome Phylogeny of Diploid Species of Isoetes (Isoetaceae, Lycopodiophyta) in the Southeastern United States. Castanea 83(2): 224–235. https://doi.org/10.2179/17-132
Sigel, EM, Der, JP, Windham, MD and Pryer, KM. 2019. Expression Level Dominance and Homeolog Expression Bias in Recurrent Origins of the Allopolyploid Fern Polypodium hesperium. Amer. Fern J. 109: 224-247. https://doi.org/10.1640/0002-8444-109.3.224
Singh, SK, Shukla, SK, Dubey, NK and Shukla, PK. 2018. Isoetes ×gopalkrishnae (Isoetaceae), a new interspecific hybrid from central India. Phytotaxa 362: 68-76. https://doi.org/10.11646/phytotaxa.362.1.5
Takamiya, M. 1999. Natural history and taxonomy of Isoetes (Isoetaceae). Acta Phytotax. Geobot. 50: 101-138.
Takamiya, M, Watanabe, M and Ono, K. 1997. Biosystematic Studies on the Genus Isoetes in Japan IV. Morphology and Anatomy of Sporophytes, Phytogeography and Taxonomy. Acta Phytotax. Geobot. 48: 89-122.
Taylor, WC and Luebke, NT. 1988. Isoetes ×hickeyi: A Naturally Occurring Hybrid between I. echinospora and I. macrospora. Amer. Fern J. 78: 6-13. https://doi.org/10.2307/1547597
Taylor, WC, Luebke, NT and Smith, MB. 1985. Speciation and Hybridization in the North American Quillworts. Proceedings of the Royal Society of Edinburgh Section B (Biological Sciences) 86: 259-263. https://doi.org/10.1017/S0269727000008216
Taylor, WC, Luebke, NT, Britton, DM, Hickey, RJ and Brunton, DF. 1993. Isoetaceae. pp. 64-75 In, FNA Editorial Committee (eds.), Flora of North America north of Mexico, Volume 2. Oxford University Press, New York. pp. 475.0
Taylor, WC, Moran, RC and Brunton, DF. 2016. Isoëtaceae, the Quillwort Family. R.F.C. Naczi, J. R. Abbott, and Collaborators, New Manual of Vascular Plants of Northeastern United States and Adjacent Canada, online edition of 2016. NYBG Press, New York [published Online: 29 April 2016]. https://doi.org/10.21135/893275471.015
Thiers, B. [continuously updated]. Index Herbariorum: A global directory of public herbaria and associated staff. New York Botanical Garden's Virtual Herbarium. Available from http://sweetgum.nybg.org/science/ih/.
Troia, A and Greuter, W. 2014. A critical conspectus of Italian Isoetes (Isoetaceae). Pl. Biosyst. 148: 13-20. https://doi.org/10.1080/11263504.2013.878409
Troia, A, Pereira, JB, Kim, C and Taylor, WC. 2016. The genus Isoetes (Isoetaceae): a provisional checklist of the accepted and unresolved taxa. Phytotaxa 277: 101-145. http://dx.doi.org/10.11646/phytotaxa.277.2.1
Tryon, AF and Moran, RC. 1997. The Ferns and Allied Plants of New England. Massachusetts Audubon Society, Lincoln.
Weldy, T, Werier, D and Nelson, A. 2019. New York Flora Atlas. http://newyork.plantatlas.usf. edu [accessed 20 November 2019]
Wood, D, Besnard, G, Beerling, DJ, Osborne, CP and Christin, P-A. 2019. Phylogenomics supports a Cenozoic rediversification of the “living fossil” Isoetes. BioRxiv (Dec 2019) 1-37. https://doi.org/10.1101/2019.12.23.886994.