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 
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