2l6 HEREDITY AND EVOLUTION IN PLANTS 



The axis of the flower terminated in a cone-shaped 

 receptacle, bearing the stalked ovules, and numerous 

 sterile scales (Figs. 97 and 98). The mature seeds often 

 contain the well-preserved fossil embryos, with two 

 cotyledons which quite fill out the nucellus, and show 

 that there was little or no endosperm. These are char- 

 acters never found in the lowest group of modern seed- 



FIG. ico. Cycadeoidca Dartoni. Tangential section through outer 

 tissues of the (fossilized) trunk, showing the very numerous seed-cones. 

 The seeds are very small (the illustration being natural size), and nearly 

 every one has a dicotyledonous embryo. There were over 500 such cones 

 on the original stem. (After a photograph loaned by Prof. Wieland.) 



bearing plants (the Gymnosperms), but only in the 

 highest group of Angiosperms, the Dicotyledons. In 

 fact, the French paleobotanist, Saporta, called some of the 

 Cycadeoids, Proangiosperms. 



145. Relation of Cycadeoidea to Modern Angiosperms. 



-The question of the ancestry of the Angiosperms is the 



most important problem of paleobotany. Although the 



