STUDIES OF SEED-PLANTS 227 



and one will find a sand-bed used for starting roots on such 

 cuttings. 



Still another artificial method of propagation from cuttings 

 is in the processes called grafting and budding. The details 

 of this method are explained in 165, but essentially it con- 

 sists in taking a small piece of stem, with buds or a single bud, 

 from one plant and attaching it to root or stem of another 

 plant. The transplanted buds grow, and when placed near 

 the root will form the entire plant above ground. This is the 

 method for obtaining standard varieties of apples, pears, 

 plums, cherries, peaches, and many other shrubs and trees. 



All such propagation of plants from parts or pieces of full- 

 grown plants without seeds is known as asexual or vegetative 

 reproduction. The propagation of plants by means of seeds in- 

 volves sexual reproduction, for most seeds originate through 

 fertilization. As we have seen, in some cultivated plants the 

 method of reproducing by seeds has been supplanted largely 

 by asexual reproduction. This has two advantages : (1) the 

 ease of starting some plants without seeds, and (2) many 

 cultivated varieties will always produce their own variety 

 from parts of themselves, but not from seeds. For example, 

 the seeds from a red apple may grow into trees which will 

 bear green-colored apples and entirely different in flavor, size, 

 etc. The only way to propagate with certainty the desired 

 variety is to take a cutting from a branch of the apple tree 

 known to bear the kind of fruit wanted and graft it on a tree 

 started from seed. The runners of a strawberry plant will 

 form new plants producing the same quality of berries, but 

 the seeds rarely do so. Moreover, in the case of seedless 

 fruits (e.g., navel oranges and seedless apples) the only possible 

 propagation is by cuttings, buds, or grafts. The millions of 

 seedless orange trees in California have descended from a 

 single tree which grew from seed but could not itself produce 

 seed. Without man's help such a variety could not have 

 multiplied. 



