66 



Commercial Gardening 



result of self - fertilization. 

 This is sexual reproduction, 

 and is vastly different from 

 the increase of numbers se- 

 cured by cuttings, layers, and 

 offsets, which are merely pieces 

 of the individual from which 

 they were taken. 



Cross-breeding* and Hy- 

 bridization. When pollen is 

 taken from the flower of one 

 variety and placed on the 

 stigma of another variety of 

 the same species, and plants 

 raised from the seeds so ob- 

 tained, the process is rightly 

 termed cross-breeding. Of the 

 hundreds of varieties now in 

 existence of the Sweet Pea, 

 Carnation, and Chinese Pri- 

 mula, none of them are hy- 

 brids, although cultivators often speak loosely of hybridizing them. A 



hybrid can only be produced by 

 ft taking pollen from the flower of one 



species and placing it on the stigma 

 of another species, such as Cattleya 

 labiata and C. bicolor, Pelargonium 

 zonale and P. inquinans, Begonia 



Fig. 55. Section of Style of Lilium Jlariagon, shoving Pollen 

 Grains on the Stigma, and sending down their Tubes along the 

 conducting tissue of the Style 



Fig. 56. Section of an Ovule, showing the entry of the 

 Pollen Tube into the Embryo Sac 



Fig. 57. Lythrum. Section of Flower, 

 showing two rows of Stamens one short, 

 one long. The Style is short. 



boliviensis and B. Pearcei. Species belonging to different genera are 

 sometimes hybridized, such as Cattleya labiata and Lcelia crispa, and the 



