58 THE STRUCTURE OF FLOWERS. 



If tbe stamens be monadelplious, and tlie union be extended, 

 it may completely enclose the usual honey-secreting surface 

 chai'actei'istic of allied genera, the result being that it can 

 secrete none at all. In such cases, insects are deceived in 

 visiting the flower, as in Genista, and some other mona- 

 delplious genera of Leguminosce. Otherwise, the honey is 

 secreted by some other source external to the staminal tube, 

 as in Linum catharticum ; in which flower five inconspicuous 

 glands occur on a fleshy ring, just opposite the stamens. In 

 Malva, the honey is found in five pits between the bases of 

 the petals, and in Pelargonium in a long tube formed by one 

 sepal, the insertion of which remains far below that of the 

 others, which are carried up by the growth of the pedicel. 

 In Laburnum* as in Orchis, instead of a secretion, the fluid 

 is only to be secured by piercing succulent tissue which is 

 found in front of the vexillum in the form of a cellular 

 cashion. 



In diadelphous species of the Leguminosce, the honey may 

 be secreted by the inner basal portion of the staminal tube,* 

 or else, and perhaps more usually, by an annular disk which 

 suiu'ounds the short pedicel of the ovary, as in Pisum. In 

 this case the honey is easily secured by the proper insects 

 as the superior stamen is free, and there is also an additional 

 facility of access by means of an oval space formed by the 

 widening of the staminal tube just above their base. 



In Cercis, the disk is very large, and the 10 stamens stand 

 in depressions around it. Consequently they are entirely free. 



The staminal tube, together with the petals, which are 

 more or less interlocked together, protect the honey from 

 being rifled by the wrong insects, f as it can only be secured 



* According to Miiller. 



t A curious additional protection occurs in Hippocrepis comosa, in 

 that the claw of the vexillum, which is elevated in a remarkable manner, 



I 



