45 



Edible Products. 



The Fruit in some varieties is long and slender; in others, nearly 

 globular, varying from 3 to 15 cm. (1 to inches) in diameter. The outside cover- 

 ing in some forms is soft and pliable, often less than one-half millimeter in thickness, 

 while in others it is hard and granular, in some of the Central American forms 

 reaching 3 mm. in thickness. The fleshy part of the fruit between the skin and 

 the seed varies greatly in thickness, but is always butyraceous in consistency, 

 though in some cases much firmer than in others. In the better varieties the 

 fibrovascular system that enters the fruit from the stem is discernible only in 

 the thin flesh in the very base of the fruit and at the base of the seed, which 

 is toward the apical end of the fruit. The seed thus appears to receive its nourish- 

 ment directly from the pulp by absorption or ceases to receive nourishment 

 before the fruit is f nlly formed. In the coarser forms the bundles can be traced 

 from the stem throughout the pulp to the point where they enter the seed, and in 

 some cases they are so prominent that the quality of the fruit is seriously 

 impaired. The tree is usually described as evergreen. In some localities, how- 

 ever, the leaves are dropped just before flowering, leaving the tree naked for 

 a short time. This is the case in Alta Vera Paz, Guatemala, where a type with 

 narrow leaves and very thick-skinned fruit prevails. Whether this deciduous 

 character is peculiar to the variety or the result of climatic conditions could 

 not be determined. 



The Seed is single, inverted, exalbuminous, spherical, or pointed, provided 

 with two more or less distinct coats, one or both of which may adhere very 

 closely to the cotyledons, though usually separable at the base of the seed; 

 or they may adhere to the flesh of the fruit and separate from the cotyledons. 

 This latter condition is observed more commonly in specimens not fully matured. 

 The surface of the outer coverings may be coarsely reticulated or granular. 

 The seed coats are frequently produced into a point beyond the apex of the 

 cotyledons. The cotyledons are nearly hemispherical in form, white or light 

 green in colour. The surface of some forms is smooth ; in others rugose. The 

 plumule is well developed before the fruit ripens and is located from 10 to 15 mm. 

 from base of seed. Concerning the seedling, Holm has pointed out that no hypo- 

 cotyl develops. He also calls attention to the curious fact that the first four leaves 

 are opposite, and by showing a differentiation into petiole and blade more closely 

 resemble the mature leaf than do the following five or six leaves, which are 

 almost scalelike. 



BOTANICAL AFFINITIES. 



The genus Persea, to which the avocado belongs, is a member of the 

 family Lauracece. Among the other more important economic members of the 

 family are cinnamon (Cinnamomum cinnamomum (L.) Cockerell), camphor (f'inna- 

 momum camphora (L.) Nees), and sassafras (Sassafras sassafras (L.) Karst.). With 

 the exception of cinnamon, they are used chiefly in medicine. The avocado is the 

 only member of the family cultivated for its edible fruit. Mez, in his monograph 

 of the family, describes forty-seven species of Persea, and states that the genus is 

 confined to the American continent, with the exception of one species in the Canary 

 Islands. On the contrary, F. Pax restricts the genus to ten species. 



VARIETIES. 



The botanical descriptions of varieties of the avocado are in nearly every 

 case too meagre and too general in their terms to be recognized, and are in 

 every case based on floral and leaf characters, no mention being made of the 

 fruit. Meissner describes four varieties, as follows : — 



Var. vulgaris. Leaves medium sized, mostly 3 to 4 inches long, Ik inches 

 broad, oval or obovate ; flowers short pediceled. West Indies, Central and 

 South America. 



