PARNASSIA AND SOME ALLIED GENERA 



Lula Pace 



(with PLATES xiv-xvii) 



The systematists have had some trouble in classifying Parnassia. 

 In an old Westphalian Flora by Karsch (15) it is placed in the 

 family Droseraceae. Hallier (12), in discussing the Saxifragaceae, 

 says Parnassia is much more closely related to the Droseraceae than 

 to the Saxifragaceae; while Eichinger (6) concludes that it should 





be placed with the Saxifragaceae as Engler (8) has it. Wettstein 

 (26) also places it there and takes Droseraceae out of the Sarra- 

 ceniales and puts it with Parietales. The possibility of finding 

 some characteristics that would help settle this question led to the 

 present study. Chodat (3) has used Parnassia to illustrate certain 

 stages in the development of the embryo sac and embryo of 

 angiosperms. 



The work was undertaken at the suggestion of the late Professor 

 Strasburger, and his continued advice was of the greatest service. 



Parnassia palustris 



Material. — The material which had been collected in Switzer- 

 land, and in the neighborhood of Bonn, Germany, was kindly placed 

 at my disposal by Professor Strasburger. It had been killed in 

 an alcohol acetic mixture (three parts of alcohol to one part of 

 glacial acetic acid) . The usual methods were followed in preparing 

 the material for cutting. The younger stages were cut 5-6 p thick 

 and the older 8-10 /*. The triple stain, safranin-gentian violet- 

 orange G, was most satisfactory, but iron-alum hematoxylin alone 

 and with Congo red was also used. 



The parts studied showed very few irregularities, or so-called 

 abnormalities. Out of several hundred ovaries sectioned, the 

 majority had five placentae, a few had four, two had three, and 

 one had only two; in the last the two placentae were not quite 

 normal in appearance. One ovary had a very irregular structure; 

 it was as if the carpels had not grown together, and more or less 



Botanical Gazette, vol. 54] 



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