PAPERS ON BIOLOGY AND AGRICULTURE 97 



ers were monocotyledonous. The same authors show 

 that even the grasses have in many cases a suppressed 

 cotyledon (3). 



SUMMARY 



1. The massive spherical proembryo without a sus- 

 pensor is considered to be a primitive characteristic. 



2. The root, perhaps the most conservative organ, ap- 

 pears to show the prevailing dicotyl type, having a region 

 of undifferentiated cell tissue from which calyptogen and 

 dermatogen are ultimately derived. This arrangement 

 corresponds to DeBary's third type of root tip. 



3. The other vascular bundles of the plant are of the 

 generally accepted monocotvledonous tvpe as is shown 

 by: 



(a) Three vascular strands to each leaf and coty- 

 ledon in the juvenile stages. 



(b) Polystelic bundle arrangement. However it 

 must be remembered that while most mono- 

 cotyls have this arrangement, some dicotyls 

 also have it. 



(c) Rhizome and epicotyl bundles are collateral 

 and without stelar cambium. However a very 

 few of the dicotyls are without stelar cambium 

 and some monocotyls are said to show traces 

 of stelar cambium. 



(d) The venation of the adult leaf is dicotyledon- 

 ous. 



(e) One cotyledon precedes the formation of a 

 second cotyledon. 



CONCLUSION 



Xelumbo lutea is phylogenetically one of the higher 

 angiosperms having both monocotyledonous and dicoty- 

 ledonous characteristics. The fibro-vascnlar bundles are 

 strongly monocotyledonous but they throw no light on 

 the origin of the seed plants. 



Finally, I wish to express my sincere thanks to Dr. J. M. 

 Coulter, to Dr. AY. J. Gk Land, and to Dr. C. J. Chamber- 

 lain for kind assistance given me while making this in- 

 vestigation. Also to Dr. W. E. Davis of Manhattan, 

 Kansas, to the authorities of the Missouri Botanical 



