174 CALIFORNIA ACADEMY OF SCIENCES. 



the whole tribe) is homologous with that of Abietinese in 

 so far as it consists of leaves of an axillary shoot, yet 

 that these leaves are not a single pair, but, as A. Braun 

 has long ago suggested in regard to Cupressinese, that 

 there is a number of leaves laterally co-ordinate and 

 connate bearing a number of ovules on their back." 

 (Bot. Gaz., vol. vii, pp. 104-105.) 



Prof. Eichler regards the scales of the female ament in 

 all conifer£e as representing nothing but simple leaves. 

 (Bot. Gaz., vol. vii, p. 39. Review of Prof. Eichler's 

 article by Prof. Geo. L. Goodale.) From the manner in 

 which the scales are arranged on the axis of the cone, as 

 well as the position of the resin ducts, as shown in plate 

 xvii, sections 14-15, S. sem^ervirens, and 16-17 ^ - S^~ 

 ganiea, this view seems the more reasonable. 



Sequoia and Taxodium are the North American rep- 

 resentatives of the tribe Taxodine^, which is intermedi- 

 ate between Cupressinese and Abietine^. Several spe- 

 cies of Juniperus and Cupressus of the Cupressinese have 

 heteromorphic foliage, also some species of Taxodium; 

 but in none is the difference so marked as in Sequoia 

 scmpervirens, which approaches the Cupressine£e in its 

 upper leaves and the Abietinese in the lower. It may be 

 that the hetermorphic character of its foliage indicates its 

 relationship to the two tribes and that environment may 

 have no influence. However, while it is interesting to 

 theorize concerning the cause of the heteromorphism and 

 the theories may be suggestive, too little is yet known to 

 form a safe basis for conclusions. 



