1 66 The Ohio Naturalist. [Vol. IV, No. 7, 



leaves. Among the species which show this peculiarity' well are 

 Riibus odoratus, R. strigosus, R. occidentalis, R. nigrobacciis, 

 and R. invisus. In the common Mock Orange, Philadelphus 

 coronarius, the cleavage plane is formed a little above the base of 

 the petiole which remains as a protection to the axillary bud. 



There are certain plants which have the hal^it of covering their 

 axillary buds with the base of the petiole. The Sycamore, Plat- 

 anus occidentalis, presents a very perfect example of this adapta- 

 tion. The reason for such a peculiarity is not easy to see. It 

 maj' be for protection, or again as in Rhus glabra it may prevent 

 the development of too many lateral buds into branches. But 

 there ma}' be no special advantage whatever. It may be a mere 

 incident to the adjustment of the leaf to the surrounding tissues. 

 Other plants which cover their lateral buds are Cladrastis lutea, 

 Rhus hirta, R. copallina, Acer negundo, Ptelea trjfoliata, Gledit- 

 sia triacanthos, Robinia pseudacacia, R. viscosa, and R. hispida. 

 In Gleditsia and Robinia there are a number of superposed buds 

 only part of which may be covered. 



The undersigned wishes to make a census by counties of the 

 pteridophytes of Ohio. To further this aim, the cooperation of 

 every science teacher and fern student is asked. Specimens with 

 full and exact data are desired and will be identified or referred 

 to some competent authority. Unless otherwi.se provided for all 

 duplicate specimens will be sent to state herbarium, O. S. U. 

 Address June 15th to August loth. University of Wooster, O. 



Lewis S. Hopkins, Troy, Ohio. 



Date of Pnblication of May Number, May 1, 1904. 



