30 BOTANY OF LA SALLE COUNTY. 



the terms, family genus, species and variety, and how 

 the last is produced. 



If we gather a dozen plants and give them a lights 

 examination we shall find no difficulty in detecting 

 many differences between them and we may also find 

 that two or more of them in some points resemble each 

 other, that they have woody branching stems, leaves 

 much alike, that each has stipules; also that the 

 flowers and fruit of one are much like those of another, 

 yet have some points of difference; we conclude that 

 they belong to the same genus but to different species. 

 If the differences are slight, as the size and color of 

 the flower or a little variation in its form or in that of 

 the leaves we call one a variety of the other. As an 

 illustration we may take the Rosacea. We have a 

 great many varieties in cultivation but when we exam- 

 in the leaves, stems, stipules, aud prickles we can at 

 once refer a great many of them to the same specie;--, 

 and when we examine the wild roses we shall also 

 find no more than 4 or 5 species, but we shall also find 

 that the flowers of the apple, pear, plum, peach, thorn 

 and several other plants are constructed on the same 

 plan as that of the rosea calyx of five sepals, corolla 

 of five petals, stamens many and seeming to be 

 attached to the head or top of the stem, the receptacle, 

 pistils one or five, more or less united; while they differ 

 greatly in leaves and other points; hence we 'place 

 them in the same family, which as the rose is the most 

 prominent plant of the group, we call Rosacea. 



There are many plants which have their flowers in 

 loose, flatheads, somewhat resembling an umbrella. 

 Here we find the carrot, parsnip, dill, caraway and 

 many other plants. In flowers and fruit these plants 

 are much alike and we make of them a family, which 

 from the peculiar arrangement of the flowersan umbel 



