674 



INDEX 



Raspberry, European red, 357 



key to principal species of, 357 



purple-cane, 357 

 Rat-tailed radish, 343 

 Ray flowers, 627 

 Receptacle, 49 

 Red cabbages, 332 



clover, 433, 435 



currant, 320 



mulberry, 255, 257, 258 



Peruvian cotton, 517 

 Repeated germination, 109 

 Reproductive activity, i 

 Retting, 279 

 Rheum, 289 



palmatum, 289 



undulatum, 289 

 Rhizoctonia, 569 

 Rhizomes, 29, 75 

 Rhododendron, 543 

 Rhodophyceae, 63 

 Rhubarb, 286 

 Ribes, americanum, 319, 320 



aureum, 319, 320 



grossularia, 319, 321 



key to important species of, 319 



nigrum, 319, 320 



oxycanthoides, 319, 321 



rubrum, 319, 320 



vulgare, 319, 320 

 Rice, 88, 202 



Canada, 206 



cultivated, 206 



large-kerneled, 206 



small-kerneled, 206 



wild, 206, 207 

 River bank grape, 499, 500 

 Robinia, 414 

 Rockmelons, 6i8 

 Root cap, 17 



crown, 157 



hair, effect of external factors upon 

 development of, 20 



Root cap, structure of, 20 

 -hair zone, 19 

 primary, 10 

 sheath, 10, 103 



system, effect of environment upon 

 character of, 14 

 primary, 91 

 temporary, 91 

 systems, 2, 10 

 adventitious, 11 

 development of, 10 

 fibrous, 10, II 

 primary, 10 

 tap, 14 



temporary, 10 

 tubercles, 413 

 Roots adventitious, 11 

 air, 16 

 classification of, based upon their 



medium of growth, 16 

 general characteristics of, 15 

 length of life of, 21 

 seminal, 10 

 soil, 16 



structure of, 16 

 tap, 14 

 water, 16 

 work of, 14 

 Rootstocks, 29, 75 

 Rosaceas, 348 



key to important genera of, 350 

 Rose family, 348 



of Sharon, 508 

 Rough oats, 131 

 Rubus, 350, 353 



argutus, 354, 355 

 bernardinus, 357 

 chamaemorus, 350 

 cuneifolius, 354, 355 

 glaucifolius, 357 

 idaeus, 357 

 invisus, 356 

 key to groups of, 353 • 



