BIOLOGY OF THE FLOWER 185 



which thus becomes dusted with pollen. On visiting 

 another flower the ripe stigma becomes dusted with pollen 

 from the body of the insect. 



Violet and Pansy. Cleistogamous flowers. The flowers 

 of the Violet and Pansy are curiously modified in all their 

 parts, and these should be carefully examined (Figs. 127 

 and 128). Note that the five free sepals are prolonged 

 downwards below their points of attachment. The corolla 

 consists of five free, dissimilar petals, the lower anterior one 

 being produced into a tubular spur. There are five stamens 

 attached by very short stalks and bearing orange-coloured 

 membraneous outgrowths at the ends 

 of the anthers (Fig. 127, 4 c). Notice 

 that the two stamens opposite the 

 spurred petal have each a long fleshy 

 nectary projecting into the spur (Fig. 

 127, 3 and 4). These secrete honey 

 which collects in the spur. The lines 

 on the petals point towards this re- 

 ceptacle, direct the insect to the honey, 

 and hence are called honey-guides. floral Diagram 

 The pistil is superior and consists of of Violet. 



three united carpels. The style is bent 

 at the base and terminates in a rounded knob (Fig. 127, 5). 

 Look for the little pit on the lower surface of the stigma ; 

 on the edge of it is a little flap. The pollen is shed on to 

 the spurred petal, and an insect, visiting the flower to 

 obtain the honey, becomes dusted with pollen. On visiting 

 another flower it. brushes the flap, leaving pollen on it. and, 

 on quitting the flower, presses the flap into the stigmatic 

 pit, and so effects cross -pollination. 



In the Sweet Violet the stigma is not globular. 



Violas and Pansies both belong to the same genus Viola, 

 but if the flowers are compared, differences will be noted 

 in the arrangement of the petals. The lateral petals of 



