BIOLOGY OF THE FLOWER 



199 



pressed. Two of them, however, are represented by small, 

 barren stumps, called staminodes [st), one on either side of 

 the stamen. Just below the single stamen, which lies under 

 the hood, is a sticky disk the rostellum (r) and on either 

 side of it is a stigmatic surface. 



Imitate the action of a bee by inserting the point of 

 a pencil into the throat of the flower, and in doing so press 

 it against the rostellum. Now remove it, and if the stamen 



Fig. 137. Purple Orchis. 1, front view of flower; 2, side 

 view of flower ; 3, pollinium ; 4, anther- and stigma- lobes ; 5, 

 pollinium removed from a flower and bending horizontally ; a, 

 anther ; I, labellum ; ov, ovary ; p, pollinia ; r, rostellum ; 

 s, stigma ; sp, spur ; st, staminodes. 



is ripe, notice that two stalked, club-shaped masses of pollen 

 adhere to the pencil (Fig. 137, 5). These are called pol- 

 linia (p), and are the masses of pollen from the anther- 

 lobes. Watch them for a moment and note that they bend 

 into a horizontal position, turn outwards a little, and are 

 therefore suitably placed for coming into contact with the 

 stigmatic surfaces when again inserted into a flower. Try 

 to brush the pollinia off the pencil and you will find that 

 the secretion glues them so firmly to the pencil that some 

 force is required to remove them. 



