1905.] NATURAL SCIENCES OF PHILADELPHIA. 577 



CRAT.EGUS IN EASTERN PENNSYLVANIA. 

 BY C. S. SARGENT. 



This preliminary sketch of the genus Cratcegus in eastern Pennsyl- 

 vania is based chiefly on the large collections and copious field notes 

 made during the last five years by Mr. Benjamin H. Smith, of Philadel- 

 phia, in Delaware, Philadelphia and Chester counties, by Dr. C. D. 

 Fretz, of Sellersville, in Bucks county principally in the neighborhood 

 of Sellersville and at Durham, and by Mr. C. L. Gruber in Berks 

 county, largely near Kutztown, and in North Heidelberg township. 

 Their careful observations and assistance have made this publication 

 possible. A few specimens collected by the late Prof. Porter in Easton, 

 Northampton county, and by Mr. A. MacElwee, of the Philadelphia 

 Museums, are also included. Previous to his death in 1904, Mr. W. M. 

 Canby, of Wilmington, Delaware, had become interested in the thorns 

 of eastern Pennsylvania, and together we had collected considerable 

 material in Bucks, Delaware and Monroe counties during several jour- 

 neys that we made for the purpose of studying the genus in this inter- 

 esting region. 



This paper is published at this time with no idea that it is exhaustive 

 or final, but to show the richness of eastern Pennsylvania in forms of 

 this genus, and with the hope that this unexpected revelation will lead 

 other botanists living in that part of the State to carry on the work of 

 investigation so ably begun by their associates. 



The following arrangement of the natural groups in which the species 

 of eastern Pennsylvania may be arranged will perhaps prove helpful in 

 the study of the group. 



CONSPECTUS OF THE NATURAL GROUPS OF THE SPECIES OF EASTERN 



PENNSYLVANIA. 



1. — Nutlets without ventral cavities. 



*Petioles short, glandless or with occasional minute glands; 



leaves obovate to oblong, oval or rarely ovate, cuneate at 



the base; corymbs many-flowered. 



Leaves coriaceous, dark green and shining above, mostly quite 



glabrous, usually serrate only above the middle, their 



veins thin except on vigorous shoots and sometimes within 



the parenchyma ; corymbs glabrous ; fruit oblong to sub- 



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