10 BULLETIN 143, U. S. DEPARTMENT OP AGRICULTURE. 



in all of the races, it tends at the same time to conceal many of their 

 distinguishing characteristics. 



The term " race," which is here applied to the groups of varieties 

 known in cultivation, seems more appropriate than the term " type," 

 which is commonly used. The word " type " in this connection means 

 nothing; the word " race," on the other hand, has a definite horticul- 

 tural meaning which seems to be applicable here. A race is a group of 

 seedlings which possess certain well-defined characteristics in com- 

 mon and will transmit these characteristics to their seedling progeny. 

 This applies to the avocados under consideration, for each race has 

 certain characteristics which never fail to be inherited by its seedlings. 



The three cultivated races may be distinguished by the following 

 characters : 



Guatemalan race. — The foliage of the Guatemalan race is not anise scented ; 

 hence, is easily distinguished from the Mexican. It is usually deep green in color, 

 a somewhat deeper green than that of the "West Indian. The flowers are not 

 so heavily pubescent as those of the Mexican. The fruit varies greatly in form 

 and size, but always has a woody outer covering one-sixteenth to one-fourth of 

 an inch thick. In some of. the cultivated forms the skin or outer covering is 

 scarcely thicker than in the West Indian race, but it is rarely so soft and pli- 

 able. The seed is comparatively smooth, and the two thin closely united seed 

 coats adhere closely to it. The seed is very rarely loose in the cavity within 

 the fruit. 



West Indian race. — In the West Indian race the foliage is slightly lighter in 

 color than in the Guatemalan, but, like the latter, devoid of the anise scent. 

 The flowers are sometimes less pubescent than those of the Guatemalan, never 

 more so, and always less pubescent than in the Mexican race. The fruits are 

 variable in form and size, but the outer covering is soft and pliable and is 

 rarely more than one-sixteenth of an inch thick. The seed is often rough, and 

 the two seed coats frequently are thick and separated, at least over the distal 

 end of the seed, one adhering to the cotyledons and the other being loose or 

 adhering to the lining of the seed cavity. 



Mexican race. — The foliage and sometimes the fruit of the Mexican race are 

 distinctly anise scented, and both are usually smaller than in the Guatemalan 

 and West Indian races. The flowers are more heavily pubescent than in either 

 of the latter. Its fruits have a very thin, often membranous skin. The seed is 

 commonly smooth; the seed coats are thin, either closely united and adhering 

 to the cotyledons (occasionally three in number), as in the Guatemalan race, 

 or separating, as in the West Indian. 



AVOCADO CULTURE IN THE GUATEMALAN HIGHLANDS. 



In reading the statements which follow it must be kept in mind that 

 the Guatemalan race of avocados is being considered. None other is 

 grown to any extent in the highlands, the Mexican race rarely oc- 

 curring in Guatemala and the West Indian being confined to the 

 lowlands. Separate paragraphs will be devoted to these two races 

 farther on. 



