SPERM VIOPIIYTES 



221 



all traces of the mesarch stru< ture have 

 disappeared, even from the cotyledons. 

 The leaves vary from narrow needles 

 (fig. 486) to broad blades and con- 

 crescent disks. When the blades are 

 broad, transversely elongated mesophyll 

 cells appear. 



. — The winged and shed- 



Staminate Strobilus. — The Staminate ding pollen grain of pine, contain 



ing 

 an early stage of the male gameto- 

 phyte. — After Coulter and Cham- 

 berlain. 



strobilus (fig. 487) is made up of spo- 

 rophylls (stamens) which are exceed- 

 ingly variable in form. In general, 



the stamen is bractlike, with sterile tip and abaxial sporangia (as in 

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

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



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

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

 the scale; the seeds become winged by tissue developed from the scale. 



