FLOWERS AND THEIR WORK. 219 



easily be seen by making the experiment. These conspicuous 

 streaks and spots are often called " honey-guides." 



Since the honey can only be reached when the keel is 

 pressed down with some force, and is produced at the bottom 

 of the tube formed by the stimsn-trough (closed above by 

 the free stamen and the standard), it can only be reached by 

 an insect with a heavy body and a fairly long tongue. The 

 flower is specially adapted to the visits of bees. It is also 

 visited by butterflies and moths. 



Sometimes a bee when working at the flowers may be seen to 

 bite through the calyx-tube and insert its tongue through the 

 hole thus made, thus reaching the honey without entering the 

 flower in the " proper " way, i.e. from the front. Many other 

 "bee-flowers" (i.e. flowers specially adapted for bees' visits) 

 show neat round holes bitten out by the bee in its short 

 cut to the honey, of which it robs the flower without render- 

 ing any service in return. 



249. Functions of the Calyx. The calyx has three im- 

 portant uses in the Bean-flower. (1) It protects the inner 

 parts of the young flower. In the bud, the stamens and 

 pistil are enclosed in the keel, the wings are folded over the 

 keel, and the standard over the wings, and the calyx is 

 wrapped over the outside of all. (2) When the flower opens, 

 the corolla expands, pushing aside the calyx-lobes, then the 

 standard curves upwards, and the flower is ready for the 

 visits of bees. The calyx then serves to hold the petals to- 

 gether and prevent their falling apart. (3) The calyx also pro- 

 tects the young fruit to some extent from becoming dried up. 



The calyx often assumes other functions, e.g. the attrac- 

 tion of insects (Monkshood, etc.), seed-dispersal (many Oom- 

 posites). 



250. The Parts of the Flower. The outer floral parts, 

 exclusive of the stamens and carpels, constitute the perianth, 

 which may either be single or, more commonly, double. If 

 the outer series of parts in a double perianth are distinctly 

 differentiated from the inner, we term the former the calyx 

 of (usually) green sepals, and the latter the corolla of 

 (usually) coloured petals. In some flowers with a double 

 perianth, it is hardly possible to distinguish between the 



