136 F. H. Knowlton — Fossil Dogivood Flower. 



Aet. XIII. — A Fossil Dogivood Flower; by F. H. 



Knowlton. 



Fossil flowers are of such rare occurrence in this coun- 

 try that when one conies to light it seems to merit an early 

 description. In working up some material from the Fort 

 Union formation (Eocene) in the Glenrock coal field, Con- 

 verse County, Wyoming, I found the specimen here 

 described, which is so obviously a dogwood "flower" that 

 there is no hesitation in referring it to Cornus. It may 

 be named Cornus speciosissima and described as follows : 



Involucral bracts 4, closely sessile, elliptical or elliptical- 

 obovate in shape, rather obtuse at the apex where the tip is thick- 

 ened. The bracts appear to have been rather thick and have the 

 veins strong and all converging in the thickened tip. The length 

 of the bracts is 18 or 20 millimeters and their greatest width 12 

 or 13 millimeters. The spread of the perfect ' ' flower ' ' must have 

 been nearly 4 centimeters. 



Although no evidence of the peduncle can now be 

 detected it is clearly the under side of the whorl of invo- 

 lucral bracts that is exposed. At the base of the best 

 preserved one of the four bracts the surface is seen to be 

 finely striate and somewhat wrinkled, and showing 

 through are five or six dark circles which undoubtedly 

 represent a part of the cluster of flowers on the upper 

 side. This completes the evidence necessary for its 

 reference to Cornus. 



Cornus has some forty or fifty living species widely 

 distributed over the three continents of the northern 

 hemisphere, with a single species crossing the equator 

 and reaching Peru. The genus is sharply separated into 

 several groups which have sometimes been given separate 

 generic rank, but it seems to me that they are all best 

 retained under Cornus. In one group which embraces 

 the majority of the species the flowers are cymose and 

 not involucrate, while in another group the flowers are 

 capitate with an involucre of large usually white bracts. 



Cornus speciosissima belongs, of course, to the invo- 

 lucrate group and as nearly as can be made out seems 

 to be most like Cornus canadensis Linne, the dwarf cornel 

 or bunch-berry, which ranges from Newfoundland to 



