42 COMPOUND ORGANS OF PLANTS. 



which it is parasitic ; others attach themselves to the stem and 

 branches of trees, as the cusouta or dodder and Visoum fla- 

 vescens or mistletoe. 



The Indian pipe (Monotropa uniflora) is one of the most 

 remarkable of our native parasites. This plant may be found 

 occasionally in the deep, rich woods of North America, during 

 the summer months. It is a singularly pallid and fungous- 

 looking plant, to which order it seems to approximate not only 

 in appearance, but also in the exercise of its functions. It is 

 fleshy, scentless, and snow-white throughout, and rises to a 

 height of from four to eight inches above the ground, bearing 

 at its summit a solitary terminal flower, which is at first 

 drooping, and in this state the plant looks not unlike a pipe in 

 appearance, but afterwards becomes erect. The whole of the 

 plant turns black in drying. 



The roots of many species of plants are not fixed to any sub- 

 stance whatever, the plant possessing a sort of locomotive 

 power. This is the case with several kinds of aquatic plants, 

 as the Lemna, or duokmeat, a little frond-like plant, which 

 covers the surface of stagnant pools with its scum-like vegeta- 

 tion, and drops its little filiform roots into the water, on the 

 surface of which it floats. So also the Fuous natans, a species 

 of marine algas, is found in the Gulf of Florida and other 

 parts of the ocean, floating many hundreds of miles away 

 from land. This plant has no distinct root, and is of course 

 found only within certain latitudes. 



Functions of roots. — The principal function of roots, con- 

 sists in drawing from the earth, or from any other medium 

 in the midst of which they are plunged, those substances which 

 serve for the nutrition of the plant. Their organization and 

 vital phenomena prove this. 



