CHAPTER 11 

 EMBRYOLOGY IN RELATION TO TAXONOMY 



Although the existing systems of classification of angiosperms are 

 based mainly on the external characters of the flowers, fruits, and 

 seeds, it is now generally accepted that cytology, anatomy, em- 

 bryology, and genetics can contribute results of considerable sig- 

 nificance in a number of doubtful cases where floral morphology 

 alone has not proved adequate. 



Many years ago Hofmeister and Strasburger indicated the possi- 

 bility of using embryological characters in taxonomy, but until the 

 invention of the microtome such investigations were confined to a 

 few skilled workers, and even their observations were not always 

 free from errors and misinterpretations. With the commencement 

 of the twentieth century, much higher standards were set in de- 

 scriptive embryology. A number of workers, particularly in Ger- 

 many and Sweden, began to discuss the bearings of their data on the 

 interrelationships of the families and genera which were being 

 studied by them. Unfortunately the preparation of the material is 

 a very time-consuming task, which requires a great deal of patience 

 and skill. The embryology of several families is therefore quite 

 unknown, and even with regard to others the existing data are often 

 quite fragmentary and inadequate. Enough has been done, how- 

 ever, to indicate that the embryological method has great possibili- 

 ties for the future (see especially Schnarf, 1933, 1937; Mauritzon, 

 1939; Maheshwari, 1945a,b; Just, 1946). 



It is difficult to enumerate all the embryological features which 

 are of taxonomic significance, for almost every structure has been 

 shown to yield results of importance. The following characters 

 are, however, considered to be of major value in delimiting the larger 

 plant groups: 



1. Anther tapetum. Whether it is of the glandular or the amoe- 

 boid type. 



2. Quadripartition of the microspore mother cells. Whether it takes 



