THE CROWFOOT FAMILY. 185 



many others are among the undesirable accessions to our native flora, 

 some of them extending over wide areas in the course of a few years. 



Iia collecting data regarding the distribution of a species, you should 

 first of all record where you have seen the plant growing. To this add 

 any observations you may have made as to its choice of locality, be- 

 havior from year to year, increase in number, liability to extermination, 

 etc. To be accepted as trustworthy, notes of this kind must be accom- 

 panied by specimens. 



With perfect specimens at hand examine the parts of 

 the plant in order. 



Roots. 



Describe their shape. What direction do they take? 

 How do those of last year differ from those of the present 

 year ? Are there any fine, fibrous roots ? if so, where do 

 they arise ? 



Note. — A comparison of different specimens shows an interesting 

 division of labor. 



The smaller fibrous roots absorb from the soil water and crude mate- 

 rials that are passed on to the leaves. In the latter, starch and other 

 reserve substances are produced, and are then carried down to the spindle- 

 shaped roots where they are stored until the next year. At the time of 

 flowering the roots of last year have already become exhausted, and look 

 old and wrinkled, while the new ones that are to take their place have 

 not nearly attained their full size. There are, then, three different sets 

 of roots performing as inany different functions. One set is absorbing, 

 another is feeding the rapidly growing plant, and the third set is develop- 

 ing into a storehouse in which wiU be laid up during the summer a supply 

 of food for future use. 



Leaves. 



Most of the leaves arise from a very short stem, and 

 appear as if they grew directly from the roots; accord- 

 ingly they are described as "radical." One or more leaves 

 are borne on the flowering stems and are spoken of as 

 " cauline." 



