The morphological and cytological distinctness of Botrychium minganense and B. lunaria in Michigan

TitleThe morphological and cytological distinctness of Botrychium minganense and B. lunaria in Michigan
Publication TypeJournal Article
Year of Publication1956
AuthorsJr. WHerb Wagne, Lord LP
JournalBulletin of the Torrey Botanical Club

1. Botrychium minganense Victorin (Ophioglossaceae) was described in 1927. It was subsequently reduced to the status of a variety, and then a form, of the nearly cosmopolitan B. lunaria (L.) Sw. Plants from California as well as numerous localities in northern North America were referred to taxon minganense. An attempt is made here to evaluate the distinctness of B. minganense and B. lunaria in localities where the two occur together in Michigan. 2. Part of the problem of discriminating critical species in this group arises from the need of good population samples and adequate specimens. A number of localities found for the two taxa under consideration here in northern Michigan made it possible to evaluate their distinctness on the basis of numerous living specimens and carefully preserved specimens. 3. The morphological distinctions between B. minganense and B. lunaria are shown to include differences in the laminar color, the orientation of the sterile blades, the relative lengths of sterile blades, the angles between the lower and upper margins of the basal pinnae, the orientation of the lower margins of the pinnae, the breadth of the pinnae, the structure of the tip of the sterile segment, as well as the late vernation stages, the juvenile leaf structure, and the form of the leaf primordium. These differences are discussed in some detail and illustrated in certain cases. 4. Both of the taxa possess marked forms of deep-shade habitats which differ considerably from one another. However, the shade form of B. lunaria (B. l. f. onondagense (underw.) Butters & Abbe) may tend to resemble typcial plants of B. minganense of normal habitat in certain designated respects. 5. Cytologically, B. minganense differs from B. lunaria in having spores of larger size, and in having n=90 chromosomes rather than n=45. Although no necessarily a primary basis of species distinction, the latter difference in chromosomes indicates that the two taxa are probably reproductively isolated. 6. The California plant which has been identified as B. minganense does not represent that taxon but rather a variety or subspecies of B. lunaria. It shares most of its characteristics with the latter species, differeing from it primarily in its laminar coloration and in its stature. 7. Botyrychium minganense does not appear on present evidence to have had hybrid origin. On the contrary, this taxon is evidently a normal species, endemic to northern North America, and belonging to the general circle of affinity that includes B. lunaria and B. simplex.