i66 
The Ohio Naturalist. 
[Vol. IV, No. 7, 
leaves. Among the species which show this peculiarity well are 
Rubus odoratus, R. strigosus, R. occidentalis, R. nigrobaccus, 
and R. invisns. In the common Mock Orange, Philadelphus 
coronarius, the cleavage plane is formed a little above the ba.se of 
the petiole which remains as a protection to the axillary bud. 
There are certain plants which have the habit 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 
may be for protection, or again as in Rhus glabra it may prevent 
the development of too many lateral buds into branches. Rut 
there may be no special ad^•antage 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 jiseudacacia, R. viscosa, and R. hispida. 
In Gleditsia and Robinia there are a number of superposed buds 
only part of which may be covered. 
The irndersigned 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 de.sired and will be identified or referred 
to .some competent authorit}'. Unless otherwise provided for all 
duplicate specimens will be sent to state herbarium, O. S. U. 
Address June 15 th to August loth, University of Wooster, O. 
Lewis S. Hopkins, 'froy, 0/iio. 
Date of Pnblication of May Number, May 1, lb()4. 
