References
For Botrychium
Hauk, W.D., C.R. Parks, and M.W. Chase. 2003. Phylogenetic studies of Ophioglossaceae: evidence from rbcL and trnL-F plastid DNA sequences and morphology. Molec. Phylogen. Evol. 28: 131-151. Google Scholar
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Wagner, W.H., Jr., and F.S. Wagner. 1993. Ophioglossaceae. In Flora of North America Editorial Committee. 1993b. Flora of North America north of Mexico. Volume 2, pteridophytes and gymnosperms. Oxford Univ. Press, New York, NY. 475 pp. Google Scholar
Wagner. 1990. In Kramer, K.U., and P.S. Green. 1990. Pteridophytes and Gymnosperms. In K. Kubitzki, ed., The families and genera of vascular plants. Springer-Verlag, Berlin. Google Scholar
Williams, E.W., D.R. Farrar, and D. Henson. 2016. Cryptic speciation in allotetraploids: lessons from the Botrychium matricariifolium complex. Amer. J. Botany 103(4): 1-14 Google Scholar