FAMILIES OF GREATEST WORTH. 61 



be set aside, or be regarded as of comparative unimportance." 

 (Lindley's Vegetable Kingdom.) 



Those who have given little attention to the subject are liable 

 to make mistakes in judging of natural affinity, because they 

 draw conclusions from unimportant circumstances, the chief of 

 which are size, form, color, and minute details. 



An artificial classification is founded on some one or a few char- 

 acters, disregarding all others. For example, it would place all 

 trees by themselves in one group, all shrubs in another; all those 

 which had five stamens together, in distinction from those which 

 had any other number of stamens, while a natural classification 

 aims to consider all structural features while young as well as 

 when mature, placing plants together which resemble each other 

 in numerous particulars, and show real relationship. 



Families of Greatest Worth. All the flowering plants grow- 

 ing in the United States are included in about one hundred and 

 seventy families. In this portion of country, most of the plants 

 which are cultivated to supply man and his domestic animals 

 with food are included within sixteen of these families. 



The Cruciferce (Mustard Family), includes peppergrass, water 

 cress, horse-radish, mustard, sea kale, turnip, ruta-baga, cabbage, 

 kale, broccoli, brussels spruts, cauliflower, coleworts, kohlrabi. 



The RutacecB (Orangeworts), includes the orange, the lime, the 

 lemon, the shaddock. 



The VitacecB (Grape Family), gives one species of grape to 

 Europe and eleven to North America, besides the beautiful Vir- 

 ginia creeper. 



The Leguminosce (Pulse family), is second- in size to the Com- 

 positcB and is one of great value. It includes peas, beans, and 

 the clovers, and is noticed in the appendix, which treats of the 

 clovers. 



The Rosacew (Rose Family), is not a very large one, but is of 



