Culture of the Sweet Pea 695 



named Gladys Unwin, which has the same color but is smaller and less 

 waved than Countess Spencer and which was a selection from Prima 

 Donna without known crossing having been effected. These varieties, 

 however, were forerunners of the new type which revolutionized sweet 

 pea culture in England and has revived and quickened the interest in 

 America. 



pollination 



We have previously noted that the pistil and stamens are enclosed 

 by the partial coalescing of the two lower petals. A very slight pressure 

 on the base of the keel will cause the pistil to appear suddenly in the 

 tip of the keel; the stigmatic surface is usually covered with pollen. At 

 the same time the stamens appear to view. If the pressure is released 

 these organs disappear as suddenly from view. 



Those who are looking for flower adaptations for the promotion of 

 cross-fertilization would say at once that here we have a mechanism that 

 is operated by the weight of a bee alighting on the keel; the pistil and 

 stamens rise up, striking the bee on the body and receiving and giving 

 pollen. Thus, as the insect visits flower after flower, natural cross-fer- 

 tilization is brought about. 



This, however, is not the case. In the first place, if we examine flowers 

 in the bud stage we find the pollen ripe. The position and condition 

 of the stigma change, for before the maturation of the pollen the stigma 

 is below the anthers. A day or two later the stigma has risen to a position 

 among the anthers and is viscid enough to hold the pollen grains. In 

 another day or two it has grown beyond the anthers. Self-fertilization 

 has taken place and the development of the legume has begun. This 

 process has taken place before the flower is fully open. Sometime later 

 the pistil is pushed out of the protecting keel by the developing pod. 



Such is the normal fertilization of sweet peas, as observed on examina- 

 tion of the flowers. Attention has been called to the fact that the sweet 

 pea stood practically still for one hundred years, and the question has 

 been asked how this can be reconciled with natural cross-fertilization. 



During the writer's experience in the field each season for three months 

 studying varieties and recording observations, not a single instance occtmred 

 of a bee alighting on the keel of the flower, nor were any bees observed 

 crawling between the wings. All the bees observed visiting the flowers 

 alighted on the outside of the wings and, in practically every case, thrust 

 the proboscis down between the right wing and the standard. In this 

 connection it may be mentioned that the bees did not show a preference 

 for any particular color, but flew from row to row and from color section 

 to color section. 



