230 FOUNDATIONS OF BOTANY 



Baldwin, the Bellflower, the Rambo, the Gravenstein, the 

 Northern Spy, and so on. Very commonly varieties do 

 not, as horticulturists say, " come true," that is to say, the 

 seeds of any particular variety of apple not only are not 

 sure to produce that variety, but they are nearly sure to 

 produce a great number of widely different sorts. Varie- 

 ties which will reproduce themselves from the seed, such 

 as pop-corn, sweet corn, flint-corn, and so on, are called 

 races. 



Only long and careful study of plants themselves and 

 of the principles of classification will enable any one to 

 decide on the limits of the variety, species, or genus, that 

 is, to determine what plants shall be included in a given 

 group and what ones shall be classed elsewhere. 



253. Order or Family. Genera which resemble each 

 other somewhat closely, like those discussed in Sect. 249, 

 are classed together in one order or family. The particu- 

 lar genera above mentioned, together with a large number 

 of others, combine to make up the Crowfoot family. In 

 determining the classification of plants most points of 

 structure are important, but the characteristics of the 

 flower and fruit , outrank others because they are more 

 constant, since they vary less rapidly than the characteris- 

 tics of roots, stems, and leaves do under changed condi- 

 tions of soil, climate, or other surrounding circumstances. 

 Mere size or habit of growth has nothing to do with the 

 matter, so the botanist finds no difficulty in recognizing 

 the strawberry plant and the apple tree as members of 

 the same family. 



This family affords excellent illustrations of the mean- 

 ing of the terms genus, species, and so on. Put in a 



