6 HORTICULTURE FOR SCHOOLS 



violet, purple. Fruit a berry but usually lacking in this country due 

 to the deficiency of viable pollen. This species fruits abundantly in 

 South America, where it is native. 



6. The potato belongs to the nightshade family. Its 

 botanical name is Solanum tuber osum. The resemblance 

 between the potato and other nightshade plants is not ob- 

 vious at first sight ; but even a casual examination of their 

 flowers and fruits reveals many similarities. There is differ- 

 ence as to size, to be sure ; but in structure they resemble each 

 other very closely. The fruits of all the nightshades are 

 strikingly similar. The potato does not bear fruits very often ; 

 the pollen is usually not viable in North America. Occasion- 

 ally, however, the green fruits may be seen on the potato vine. 

 While not edible, they nevertheless are comparable with the 

 tomato, both being seed-bearing berries. The fruits or berries 

 of the potato are much larger than those of the common 

 nightshade, but here again an examination of the structure 

 of each will show how close is the resemblance between them. 



7. Inter-grafting. It is possible to graft a tomato on a 

 potato, or a tomato on the common nightshade. Of course, 

 the graft is of no commercial importance, and is of signifi- 

 cance only in a scientific sense. But it illustrates in a graphic 

 way the close relationship between the potato, the tomato, 

 and the nightshade, all regarded by some authors as species 

 of the genus Solanum. 



8. Domestication. All cultivated plants came originally 

 from the wild, directly or indirectly. Some of them were 

 brought under domestication so many centuries ago that 

 there is no definite pcord of the date or process. Some, such 

 as rice and the grape, were under the care of man before the 

 advent of written history, and the early beginnings of domesti- 

 cation are, therefore, shrouded in the haze of the distant past. 



We know, however, the broad outlines of the narrative, 

 uncertain though its beginnings are ; and we can pick out the 

 different threads and follow each, step by step. We know 



