DISTRIBUTION OF THE ORCHIDACEAE IN MICHIGAN.* 



H. T. DARLINGTON. 



The Orchidaceae, unlike many other plant families, contains no adventive 

 species within the state, so far as we know ; again, the species are, generally 

 speaking, uncommon, so that the family lends itself more readily to a rather 

 definite treatment so far as the distribution of species is concerned, than 

 most other families. It is known to be quite cosmopolitan, so that where 

 marked contrasts in distribution are observed, they are due to quite natural 

 causes, except in those sections of the state where cultivation or drainage has 

 rendered certain species less plentiful. 



Following the nomenclature of the Illustrated Flora, we have in the state 

 twenty-four genera of the Orchidaceae, including nearly fifty species. A study 

 of the distribution of these species has been based on an examination of many 

 herbarium specimens, as well as on the records obtained from reliable lists of 

 plants. Points of collection have been located on small maps of the state 

 showing the counties and principal rivers. In general, the county has been 

 made the unit of location. The writer realizes that distribution records of 

 thif?^ind can never be complete. The principle of priority has been followed 

 as nearly as possible when a plant species has been reported more than once 

 from any county. As many plants have been examined as possible. When 

 this could not be done, records were from men whose ability as collectors 

 was known. 



The one point which perhaps stands out most clearly from an examination 

 of the distribution maps is the sparse orchid flora of the Jack Pine region. 

 In the Southern Peninsula, this region extends roughly from a line drawn 

 east and west through about the southernmost point of Saginaw Bay north to 

 a line drawn from Thimder Bay west to the head of Grand Traverse Bay. 

 Apparently the greater number of species are found south of this region. The 

 evidence for this may be partly due to the fact that the northern counties 

 have not been so carefully examined, yet it seems clear that our orchid flora 

 is richer in the deciduous than in the coniferous areas. 



There are probably three or four species in the state belonging to this 

 family which have not yet been reported. On the other hand, it is very doubt- 

 ful whether the Crane-fly Orchis, Tipularia unifolia (Muhl.) B. S. P., reported 

 for this state, has ever been found here. There is no record of its having been 

 collected here during the last sixty years, so far as we have been able to deter- 

 mine. Dr. Dennis Cooley, whose botanical work in this state was done between 



♦This article was written at the suggestion of Dr. E. A. Bessey, whose encourage- 

 ment at all times has been appreciated. 

 21st Mich. Acad. Sci. Kept., 1919. 



