332 PLANT MORPHOLOGY 



ter representing sterile microsporophylls (Fig. 282 A). The microsporo- 

 phylls (stamens) were long-stalked and bore two to five erect microspo- 

 rangia at the tip. 



The ovulate strobili were composed of bracts and ovules, the latter 

 borne on secondary axes in the axils of the bracts (Y'lg. 282/i). Thus the 

 strobilus was compound. The integument of the ovule had an outer 



Fig. 281. Cordaites laevis. Restoration of foliage-bearing branch with numerous strobili; 

 a large bud is shown at the right. {From Arnold, after Grand'Eury.) 



fleshy and a middle stony layer, but no inner fleshy layer. The nucellus 

 was entirely free from the integument, its peripheral region being trav- 

 ersed by one set of vascular strands, another set occurring in the outer 

 fleshy layer of the integument. A prominent nucellar beak and pollen 

 chamber were developed, indicating that the sperms were swimming. 



Gametophytes. As in the Cycadofilicales, a group of cells has been 

 found within the pollen grain, but it is uncertain whether they represent 

 vegetative or spermatogenous tissue. The female gametophyte was simi- 

 lar to that of modern gymnosperms. There were two archegonia, sepa- 

 rated by a beak-like upgrowth of gametophyte tissue. This is also a 

 feature of the modern genus Ginkgo. The seeds were very similar to those 

 of the Cycadofilicales. In neither group have seeds wuth embryos been 

 found. 



