294 Minnesota Plant Life. 



spherical stones and arranged in clusters of three or four; the 

 choke-cherry, with fruits of a red color or sometimes nearly 

 black, in clusters like those of the currant ; and the black cher- 

 ries, forming their fruits in clusters similar to the last men- 

 tioned, but always dark purple or black in color and somewhat 

 flattened vertically. The choke-cherry can be distinguished 

 from the black cherry by the very astringent taste it possesses. 

 The fruit of the black cherry is sweet and not so astringent. 



Comparison of different types of rose fruit. The fruits in 

 the various sorts of roses appear to be quite dissimilar, while 

 in reality they are but different elaborations of the same gen- 

 eral types. It may serve to explain them if they are briefly 

 compared with each other and described as modifications of 

 some common fundamental form. In the first place it should 

 be noticed that the number of carpels in the flower varies 

 from one in the plums and peaches to fifty and more in the 

 strawberries. These carpels are generally separate from each 

 other, forming independent pistils; but in the spiraeas, apples, 

 mountain-ashes and their relatives, the small number of carpels, 

 ordinarily four or five, are produced close together, so that they 

 seem almost to blend in one body. In other instances the 

 carpels are quite distinct and separate, as in the strawberry. 

 An apple may be compared to five almond nuts placed close 

 together and surrounded by a thick fleshy layer. Each seg- 

 ment of the apple core is a ripened carpel containing one or 

 two seeds. A strawberry may be compared to an apple core 

 with the flesh removed and the number of carpels increased to 

 fifty or more, very much diminished in size and situated on the 

 surface of a swollen fleshy axis. A plum, or cherry, or peach, 

 may be compared to one segment of an apple core with the 

 papery membrane greatly thickened and converted into two 

 layers, the outer soft and pulpy, the inner hard and stony. A 

 blackberry may be compared to a strawberry in which all the 

 nutlets have matured after the fashion of plums or cherries. 

 A raspberry may be compared to a strawberry with a dry pulpy 

 centre and plum-like nutlets which separate from their axis in 

 a group. The curious bur-like fruit of the agrimony may be 

 compared to an apple of conical shape with the fleshy part 

 modified into a layer on which are arranged numerous prickles 



