KEVISION OF THE NORTH AMERICAN SPECIES OF GAYOPHYTUM 



AND BOISDUVALIA. 



BY WILLIAM TRBLEASK. 



Though few in numbers, our species of Gayophytum and 

 Boisduvalia are difficult because of the great variability of 

 several species, and as the naming in herbaria is usually 

 much confused, it is hoped that the following revision may 



facilitate 



determination 



collections. In its 



material 



preparation I have examined the 

 mann herbarium and the general herbarium of the Missouri 

 Botanical Garden, and the collections of Columbia College, 

 Harvard University, the California Academy, and the 

 United States Department of Agriculture, for the use of 



wish to express my 



banks. Several western 

 me under obligation by 



tributing specimens for the Garden herbarium. 



Gayophytum, Juss. Ann. Sci. Nat. 1832, xxv. 18, pi. 4; 

 Bentham & Hooker, Gen. PI. i. 786, 789. 



Gayophytum is a small genus of Onagraceae of the as- 

 pect of the paniculatum group of Epilobium, and also more 

 or less similar in appearance to species of Oenothera of the 

 group Sphaerostigma. 

 ing its seeds quite destitute of a coma 

 ovary and fruit, and isolated pollen g 

 similar habit and with equally reflexed sepals, may 

 tinguished from it by their more elongated calyx-tu 

 4-celled ovary, and the prevailing color of their flc 

 yellow, while the flowers of our Gayophytums are v 



From the former it differs bv hav 



Oenotheras 



rose-purple. The bark is very frequently papery-exfoliat- 

 ing at base, as in some Epilobiums. 



The geographical distribution of the genus is peculiar. 

 The species represented in our flora are plants of the 



on of the west. One or two other represent- 



mountain 



6 



Reprints issued Jan. 5, 1894. 



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