THE POTATO 



9 



tube widens out suddenly from a very short straight tubular 

 part at the base. Its colour is purple or white with a yellow 

 centre. Attached to the corolla-tube are the five stamens, which 

 stand up prominently in the centre of the flower around the 

 style. Each of these has a short filament and a large yellow 

 anther. The anthers open by round pores at the tip. The pistil 

 consists of two carpels united together to form a slightly two- 

 lobed ovary surmounted by the style bearing a green, sticky, 

 two-lobed stigma. The ovary has two cavities almost filled by 

 the projections of the partition which bear the numerous ovules. 

 The two carpels are placed obliquely in the flower. 



The flowers secrete no honey, and though conspicuous are 

 rarely visited by insects. In the 

 open flower the stigma projects 

 some distance in front of the 

 stamens, and is curved down- 

 wards. An insect approaching 

 the flower would thus touch 

 the stigma first and then come 

 in contact with the tips of the 

 stamens where the pores, by 

 which the pollen escapes, are 

 situated. In studying the pol- 

 lination arrangements of this 

 flower we must bear in mind that we are dealing with cultiv- 

 ated varieties, and also that the plant is an exotic one and is 

 not being studied in its natural surroundings. 



Unfertilised flowers wither and fall off, but when fer- 

 tilisation has been effected this only happens to the corolla 

 and stamens. The style becomes detached from the summit 

 of the ovary, leaving a small scar, and the ovary enlarges 

 into the fruit. This is a berry, the two component carpels 

 of which are indicated from the outside by a slight groove. 

 On cutting it across, the seeds in the two cavities will be seen 

 surrounded by the thick, more or less succulent walls of the 

 ovary. 



The seedling plant carries up the pair of seedling leaves, which 

 expand and turn green. The buds in the axils of the seed-leaves 



FIG. 4. Flower of the Potato cut in half 

 lengthwise. (After Baillon.) 



