THE FRUIT 71 



composition and color on all plums but the quantity varies 

 greatly and gives it differentiating value in separating varieties. 

 It suffices to describe it as light, thin, scant, heavy. Sometimes 

 there is a trace of bloom on cherries and nectarines but on 

 peaches and apricots it is so obscured by the pubescence of these 

 fruits as to be negligible. It is customary to give colors to 

 bloom, as blue, gray, or lUac, but all bloom is white and the 

 seeming color comes from the color of the skin. Heavy bloom is 

 sometimes wax-Wke. 



108. Skin characters of drupes. — Few characters of the skins 

 of drupes are helpful to the systematist. The skin may be 

 thick or thin, tough or tender. Perhaps the most noteworthy 

 character is that of adherence to the flesh; in most varieties 

 of drupe-fruits the skin adheres tightly to the flesh, but in some 

 it readil}^ peels off, giving rise to the terms adherent or free. 

 In some plums, especially in several native species, the skin is 

 markedly astringent. 



The pubescence on the skms of peaches sometimes furnishes 

 clues to identification in the length of hairs and in their num- 

 bers. The nectarine is a smooth-skinned peach between which 

 and the long- and thick-haired Rochester there are all grades 

 in length and quantity. Some cherries, especially Priinus 

 tomentosa, and a few plums have some or many hairs. Plums 

 and cherries are described as hairy, but peaches and apricots 

 are usually spoken of as pubescent, tomentose, woolly, or felted. 

 The amount and character of the pubescence on the drupes 

 varies greatly with soil and climate. 



109. The flesh of drupes. — The color of the flesh is a plain 

 dividing line between groups of drupe-fruits. In all there are 

 red-, white-, green-, and yellow^fleshed sorts, while in some plums 

 and cherries there is a purple tint. There is almost no variation 

 in the color of the flesh in any of the drupes, so that a distinct 

 color that can be described positively, as white, yellow, or red, 

 sets an absolute mark on a variety. The color of the juice in 

 cherries is just as positive a mark; one great group of sour 

 cherries, the Amarelles, have colorless juice ; another, the Morel- 

 los, have reddish juice. In the red- juiced cherries, the red may 

 be light, dark, or purplish. Some varieties of all drupes are 

 much juicier than others; thus there are juicy and dry sorts. 



