356 THE FLOWER 



larger insects can see them from a distance. The 

 flower often has nectaries, little masses of gland cells 

 which secrete a sugary solution, and this nectar is 

 the main attraction of many flowers to nectar-eating 

 insects. In the case of butterflies and moths it is the 

 sole attraction. The ripe anthers and ripe stigmas are 

 commonly held in such a position that the insect has 

 to brush past them in reaching the nectary. 



A very common arrangement is that in which the 

 anthers ripen first, and the filaments bend so as to 

 bring the anthers into the path of the insect, while 

 later on the stigmas ripen and bend into the same 

 position. Such a flower is called protandrous.^ An 

 insect visiting the flower in the first stage will carry 

 away poUen, and this wiU be rubbed on to the stigmas 

 directly it visits a flower in the second stage, since 

 the insect will brush the anthers and stigmas in the 

 two flowers with the same part of its body. 



Thus in the buttercup the nectaries are on the inner 

 sides of the petals near their bases. When the petals 

 first open the centre of the flower is occupied by a mass 

 of anthers concealing the undeveloped stigmas. The 

 first anthers to open are those on the outside, next 

 the petals, and the ripening of the anthers progresses 

 gradually inwards to the innermost ones, the ripe 

 anthers bending outwards. This is the " male stage " 

 of the flower. If a large insect visits the flower it aUghts 

 in the centre on the mass of anthers and pushes its 

 head down between these and the petals to get at the 

 nectar. In doing so pollen will adhere to the lower 

 side of its head or body. By the time the last anthers 

 have opened the carpels have grown up in the middle 



' Greek TTpwrog, first, and dv^p, dvdp6g, man, because the male 

 elements (pollen) ripen first. 



