90 



THE AMERICAN BOTANIST. 



Fig. 6. 



is borne in the position most favorable to the reception 

 of the pollen. 



Plants have many ways of securing pollenation and 

 the stigmas vary in shape to suit their needs. In flowers 



that are poUenated by insects the 

 stigmas are seldom very conspicu- 

 ous, but in wind-pollenated plants, 

 such as grasses and sedges (fig. 6, 

 6), they are often long and feathery 

 to enable them to catch any pollen 

 that may happen to be floating by. 

 Frequently, too, the stigma is not 

 terminal, but the stigmatic surface 

 may extend down one side of the 

 pistil. For some interesting exam- 

 ples of stigmas the student may examine the blue flag 

 (Iris), the evening primrose (Oenothera), the poppy (Pa- 

 paver) the pitcher plant (Sarracenia) , the spatterdock 

 (Nuphar) and the lily. The principal office of the style 

 seems to be to hold the stigma in the proper position for 

 pollenation. In some cases it is very long as in Indian 

 corn where each strand of the "corn-silk" is a single style. 

 Ordinarily the style grows from the top of the ovary, but 

 occasionally it is produced at the side and in the mint family 

 it grows from the base. 



In five-parted flowers there should be at least five pis- 

 tils but it is seldom that a flower contains this number ot 

 separate pistils. Examples of this, however, ma3^ be seen 

 in the flowers of columbine (Aquilegia) and live-for-ever 

 {Sedum telephium). There are often less than five, as in 

 the cherry, where the others are supposed to be sup- 

 pressed ; but more frequently what at first sight appears 

 to be a single pistil consists of the original number joined 

 together. There are various ways of ascertaining whether 

 this is so or not. In a compound pistil there is usually 

 a little ridge where each pistil joins the others and 

 along which the seed pod opens later, as in the violet and 

 pansy. Often only the ovaries are consolidated as in the 



