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. 100. — Cycadeoidea 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 Angiosperm^s, the Dicotyledons. In 

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

 Cycadeoids, Proangiosperms. 



145. Relation of Cycadeoidea to Modem Angiosperms. 

 — The question of the ancestry of the Angiosperms is the 

 most important problem of paleobotany. Although the 



