ROOTS THEIR STRUCTURE AND FUNCTION 55 



Slips or cuttings from certain plants develop adventitious roots 

 from the stem or leaves and start new plants by this means. Many 

 plants, like the strawberry, send out horizontal stems called 

 " runners " from which adventitious roots develop and produce 

 other individuals. 



Climbing Roots. The stems of poison ivy, trumpet creeper, 

 and some other vines grow climbing roots which act chiefly as 

 means of support. These plants have ordinary soil roots, also, 

 for the purpose of absorption. 



Parasitic Roots. In a few plants, such as the dodder and mistle- 

 toe, parasitic roots develop from the stem, penetrate into the 

 tissue of some other plant, and absorb food from their victim, 

 often causing its death or serious injury. The dodder is parasitic 

 upon clover, golden-rod, and other plants; the mistletoe usually 

 grows upon the oak. 



REFERENCES FOR COLLATERAL READING 



Natural History of Plants, Kerner and Oliver, Vol. I, Part 1, pp. 82-99; 

 Part 2, pp. 749-767; Textbook of Botany, Gray, pp. 27-33; The World's 

 Great Farm, Gaye, pp. 124-128; Plant Relations, Coulter, pp. 89-108; 

 Elementary Studies in Botany, Coulter, pp. 253-270; Plant Life and its 

 Uses, Coulter, pp. 123-141; Experiments in Plants, Osterhout, pp. 87-162; 

 Plants and their Children, Dana, pp. 99-112; Outlines of Botany, Leavitt, 

 pp. 36-45; Botany all the Year Round, Andrews, pp. 120-142; First 

 Course in Biology, Bailey and Coleman, pp. 32-48; Civic Biology, Hunter, 

 pp. 71-83. 



Characteristics of Roots: 



1. No leaves, or flowers. 



2. Growth back of tip, not at nodes. 



3. Root cap for protection, instead of bud scales. 



4. Irregular branching. 



5. Turn towards gravity against light. 



6. Internal structure. 



Root system consists of 



Primary root, or fibrous roots. 

 Secondary roots. 

 Root hairs. 



