Slender ClifF-Brake 95 



Crypto gramma Stelleri (S. G. Gmel). Prant, Engler's Bot. Jahrb. 3: 413. 

 1882. 



Pteris Stelleri. S. G. Gmel., Nov. Comm. Acad. Sci. Petrop. 12: 519. 

 P/. XII,/. I. 1768. 



Pellaa Stelleri. Watt, Can. Nat. : 3 158. 1867. 



Pteris gracilis. Michaux, Fl. Bor. Am. 2: 262. 1803. 



Pdlaa gracilis. Hooker, Sp. Fil. 2: 138. PL CXXXIII. B. 1858. 



I HAVE not been able to obtain leaves of Crypto gramma Stelleri 

 portraying earlier stages of leaf-development than the leaves 

 figured in PI. XXI, but from the figures the general develop- 

 ment of the form and venation of the leaf can be seen. 



It will be noted that the venation is pinnate, and that when 

 new segments form on the leaf, many duplicate to a certain 

 extent the earlier segments. For instance, compare Figs, i a, 

 2 a, 4 a, 6 a, 8 a (PI. XXI), and 2 a (PI. XXII). 



It will also be noted that the fertile leaf figured has no ter- 

 tiary segments (PI. XXII, Fig. i). Tertiary segments are often 

 lacking in the mature leaves. 



The incision by means of which the first basal primary 

 branch of the mid vein of any one of the leaf's segments is set 

 apart to constitute the midvein of a new segment sometimes 

 occurs while the midvein of the existing segment is little de- 

 veloped, and before other incisions occur in this segment : which 

 often gives the subdividing segment the appearance of being cut 

 vertically into two nearly equal parts. 



The midveins in newly formed segments are sometimes not 

 developed beyond two simple primary branches. In segments 

 in later stages of development they are conspicuously developed. 



In the transformation of the sterile leaf into a sporophyll, 

 the leaf's 'petiole lengthens, and the leaf-blade's margin recedes 

 slightly and folds backward on the sides of the leaf's segments 



