98 THE STORY OF THE PLANTS. 



another in general aspect, they have still among 

 themselves a curious variety of marriage customs. 

 I will mention two only. In gorse, a flower which 

 everybody can easily examine, the wings have 

 two little knobs at the sides for the bee to alight 

 upon. As he does so, the corolla springs open 

 eiastically, and dusts him all over with the fer- 

 tilising pollen. But once it has burst, it remains 

 permanently open, the keel hanging down in a 

 woe-begone way, so that no bee troubles himself 

 again to visit it. This saves time for the bees, 

 and enables them quicker to fertilise the remain- 

 ing flowers; for when they see a gorse-blossom 

 *' sprung," as we call it, they recognise at once 

 that it has already been fertilised, and they know 

 they can get no food by going there. In the 

 lupine, on the other hand, and in the common 

 little English birdsfoot-trefoil, the keel is sharp 

 at the point, and the pollen is shed into it before 

 the flower fully opens. When a bee lights on the 

 knobs at the side, he depresses the keel, and the 

 pollen is pumped out against his breast in the 

 most beautiful manner. . I hope my readers will 

 try some of these experiments in summer for 

 themselves, and satisfy their own minds w^hether 

 these things are so. 



So far, we have dealt mainly with flowers in 

 which the petals are all still distinct and separate. 

 But in a great many plants, the petals have grown 

 together, so as to form a single piece, a ''tubular 

 corolla," as we call it. This arrangement is very 

 well seen in the harebell, the Canterbury bell, the 

 heath, and the convolvulus. How did such an 

 arrangement arise ? Well, in many flowers even 

 with distinct petals there is a slight tendency for 



