PENNSYLVANIA TREE FERN COMPRESSIONS 9 



Caulopteris Lindley and Hutton, 1832 



Description . — Stem of tree fern (compression or impression); 

 leaf scars in more than two vertical rows, forming either diagonal rows 

 or whorls; leaf scars round or oval, entirely isolated, or connected in 

 vertical direction with the next scar, or covering the whole stem; trace 

 of vascular tissue with stewartiopteroid or stipitopteroid configuration, 



Caulopteris sp. A to D 



It will be shown in the discussion section that there is no 

 sound basis for delineating natural species within this genus. In this 

 paper an artificial and preliminary separation of form-species based on 

 differences in height and in height-width ratio was made (text fig. 6). 

 The cutoff points are 1.3, 1.9, and 2.6 for the height-width ratio and 

 100 mm for the height. The different form-species were designated by 

 letters from A to D. Measurements of specimens assigned to Caulopteris 

 species A through D are given in table 3; and these species are illus- 

 trated on text figure 7. A few specimens show additional features and 

 are. described separately on pages 10 and 11. 





















200- 













/", 

















1 / 



/ / 

















/ „ / 





150- 













/ S' 

















; / 



/'d n , 















1 • / 

















\_x 



" 



























K' 





100- 

























- 





















/ 

 / 



/ 



f 



«/ 



¥ R 

 »1 . 



\ 

 \ 

 \ 

 \ 



1 









/ 





1 # 





• i 



1 %' 





50- 



1. 



A 



• 



1 



A 



i 

 i 



• 

 • 



1 



1 

 / 



• / 

 • 



1. ' 





■ 









/ 

















i 



• 

















*u 



• 













7 



.0 







1.5 



' 



| 1 1 1 1 | ! 



2.0 25 



3.0 



Height to width ratio 



Text fig. 6 - Plot of height versus 

 height to width ratio of leaf 

 scars of Caulopteris specimens 

 from Illinois. 



Text fig. 7 - Typical examples of the 

 form-species of Caulopteris from 

 Illinois. Scale bars represent 1 cm 

 Letters A to D correspond to desig- 

 nation of species; E - Caulopteris/ 

 Psaronius sp.; F - Caulopteris 

 wortheni Lesquereux. 



