322 



MORPHOLOGY OF THE ANGIOSPERMS 



with that of the plumule; admotive, when the plumule-hypocotyl-radicle 

 axis was curved and the cotyledon axis at an obtuse angle with it. Dis- 

 tinction between these two types may also be difficult to make. 



The Axis in the Embryo. Much of the confusion in the application of 

 terms to the embryo is related to the axis. Under the older terminology, 



Fig. 122. Longitudinal sections of monocotyledon embryos showing pseudoterminal 

 position of cotyledon attained by dominant growth of cotyledon and accompanying 

 change of axis from straight to curved, and plumule from terminal to so-called lateral. 



A, Lccrsia clandcstina; B, Guzmannia tricolor; C, Costits; D, Aechmca miiikita; 

 E, Tillanchia vestita; F, Kuratas amazonica; G, Onjza sativa. (A, G, after Schlickum; 



B, D, E, F, after Gatin; C, after Boyd. ) 



the axis was considered to consist of the "caulicle," or "embryonic 

 stem," and the "radicle," the "embryonic root." But these terms have 

 been less used in recent years. In most embryos, no true stem has yet 

 been formed; the part termed caulicle is usually the hypocotyl. Com- 

 monly, there is a root primordium, but usually no true root is present 



