ACHLYA DeBARYANA HUMPHREY AND 

 THE PROLIFERA GROUP 



W. C. COKER 



(With Plate 78, Containing 13 Figures) 



Achlya DeBaryana Humphrey is the Achlya polyandra of 

 DeBary, not of Hildebrand, as Humphrey has shown ;^ and as 

 Hildebrand's name is the older and appHes to another plant, 

 Humphrey's name should be used. Recent writers on the mor- 

 phology of this species have ignored this and still call the plant 

 Achlya polyandra DeBary. There are now recognized three very 

 closely related species, forming what was called by Humphrey the 

 prolifera group, which from the work of recent writers are be- 

 coming more and more difficult to separate. They are Achlya 

 prolifera (Nees) DeBary, A. DeBaryana Humphrey, and A. 

 americana Humphrey. Humphrey was himself aware of the very 

 close resemblances of these species and remarked upon it; but on 

 account of DeBary's assurance of the autonomy of the first two, 

 felt called on to continue the distinction. According to DeBary, - 

 A. DeBaryana (his A. polyandra) has antheridial branches that 

 arise from the same main hyphae that bear the oogonia, and then 

 branch and extend out to the oogonia on the branches from 

 which they arose (which is most common) or to oogonia on other 

 threads. In A. prolifera, on the other hand, he says that the 

 antheridial branches are diclinous, always arising from other 

 hyphae than the ones that bear the oogonia and that all oogonia 

 are furnished with antheridia. He also says that while A. proli- 

 fera has oogonia with abundant pits, the oogonia of A. DeBaryana 

 is without them. Achlya americana has antheridial branches that 

 arise from the same hyphae as the oogonia, and it also has 



^ The Saprolegniaceae of the United States. Trans. Amer. Philos. Soc. 

 17 : 1892. 



^ Untersuchungen iiber Peronosporeen und Saprolegnieen. Beitr. zur Morph. 

 und Phys. der Pilze, IV Reihe. 1881. 



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