THE ORDER ROSACEA 105 



belong almonds, apricots, cherries, nectarines, peaches and 

 plums, of which some forty odd species are more or less culti- 

 vated, an assemblage of natural esculents probably unsurpassed 

 by any other genus in variety and value of its products. Most 

 of the drupe-fruits are natives of the north temperate zone. 

 Some botanists divide the genus Prunus into several genera. 



152. Tribe Rubeae, the brambles. — In this division of Rosacea 

 the pistils are several or numerous and become drupelets at 

 maturity. While there are two ovules, the seed is usually soli- 

 tary, one ovule aborting. The plants are perennials or in a few 

 species soft-wooded biennials. The plants are erect, decumbent, 

 trailing, or in one or two species climbing, and, with but few 

 exceptions, thorny or prickly. Only one genus, Kubus, is put 

 in this division of Rosaceae, but here belong blackberries, dew- 

 berries, and raspberries, and several less well-known sorts, which 

 pass under the general name of brambles, the fruits of which 

 are called berries, although they are not true berries but aggrega- 

 tions of drupelets. The brambles are of wide geographical dis- 

 tribution, most of which, however, are in the north temperate 

 zone. 



153. Tribe Potentilleae, to which belongs the strav^berry. — The 

 members of this tribe differ widely from the three other divisions 

 of Rosaceae in which fruit-growers are interested. The carpels 

 are many and ripen into dry achenes which are not inclosed at 

 maturity. Of the several genera commonly put in the tribe, 

 pomologists are interestsd in but one, Fragaria, the strawberry, 

 which is separated from the other plants in the group by its 

 pulpy and much enlarged receptacle. The differences between 

 the low herbaceous strawberry and the pomes, drupes, and 

 brambles in plant and fruit would seem to separate the genera 

 to which they belong so widely as to put Fragaria in quite 

 another division of the plant kingdom, but the similarities in the 

 structure of the flowers bring them all into Rosace®. 



