Sl'ERMA'I'Ol'IlVnvS 



22 1 



all traces of (he mcsarcli sln.u;lurc lia\c 

 disapj)cared, c\-cii from llic colylccloiis. 

 Tile lea\'cs vary from narrow needles 

 (fig. 4S6) to broad blades and con- 

 crescent disks. When the Ijlades are 

 broad, transversely eloTigated mesophyll 

 cells ajjpear. 



Staminate strobilus. — The staminate 



Fto. 48Q. — The winged and shed- 

 ding pollen grain of pine, containing 



Strobilus (fig. 4S7) is made up of Sljo- ^'" o^^""'-^' "'^ec of the male gameto- 



phvte. — After Coulter and Cham- 

 rophylls (stamens) which are exceed- bfrlain. 



ingly variable in form. In general, 



the stamen is bractlil<e, with sterile tip and abaxial sporangia (as in 



cycads and podocaqjs), the sporangia most frequently two in number 



(fig. 488), though sometimes more numerous; but in the araucarians 



Fro. 490. — Various views of the ovuliferous scales and ovules of pine; on upper sur- 

 face are borne two ovules (megasporangia) with rnicropylcs directed towards the base of 

 the scale-, the seeds become winged by tissue develo[n'd [rum the scale. 



