CONSPICUOUSNESS OF FLOWERS 83 



Reference has already been made (p. 72) to the various ways in which the 

 pollen of anemophilous plants is protected. 



Flowers employ matiy methods of enticing insects suitable for tratisferrittg pollen : 

 colour and odour, the proffer cf pollen and nectar, provision of a shelter, Sfc. 



It is the petals or perianth-leaves which, owing to their bright colours, play 

 the leading part in bringing about Conspicuousness in flowers, and in enticing 

 cross-pollinating insects to visit them. If one side of the corolla is not visible 

 to insects on the wing, it is less brightly coloured than the side which they are able 

 to see. In species of Gagea (G. pratensis, arvensis, sylvatica, and others), for instance, 

 the perianth leaves which are spread out like a star in the sunlight, are shining yellow 

 on their inner side, while externally they are of a dull yellow, which is rendered 

 even less conspicuous by a green dorsal stripe. The opposite is true for urceolate 

 or campanulate flowers, such as those of species of Campanula, for in these the 

 inner side, which is not seen by insects during flight, is less conspicuous than 

 the outer which is exposed to their view as they wander about in quest of food. 



When the petals are modified into nectaries, or have not been fully developed for 

 other reasons, the sepals in many cases take over the function that more properly belongs 

 to the petals. This is a very common occurrence, and it may suffice to mention here 

 some Ranunculaceae, such as Anemone nemorosa and ranunculoides, Hepatica triloba, 

 Trollius europaeus, Eranthis hyemalis, Pulsatilla pratensis, Aconitum Napellus, &c. 



The petals are frequently helped by the sepals in the work of allurement, so 

 that the two outermost whorls of the flower minister to the same end. The 

 inner side of the sepals in Nymphaea alba, for instance, which is turned towards 

 the air and light, is coloured white like the petals, while the under side that lies 

 upon the water and is not visible from above, has a green colour. The inner 

 side of the sepals of Comarum palustre is coloured a dark purple brown, so that 

 the flower is made much more conspicuous, for though the petals are similarly 

 coloured, they are only about a third of the size of the sepals. 



More rarely the stamens serve as a means of allurement. The willows may 

 be cited as the best known examples, their yellow or red anthers enticing numerous 

 insects to visit them. Sometimes filaments are of a bright colour. In species of the 

 genus Verbascum, they possess a covering of violet, purple, yellow, or whitish hairs, 

 which is often very conspicuous. Even in the case of Thalictrum aquilegifolium, 

 and Plantago media, which are anemophilous, the filaments are coloured violet. 

 (Cf p. 69, note.) 



Still more rarely do the carpels play the part of alluring agents, e. g., in Caltha 

 palustris and Comarum palustre. 



It more frequently happens that flowers or inflorescences are made more 

 conspicuous by coloured bracts, e. g. the purple bracts of Melampyrum arvense, 

 the azure-blue ones of M. nemorosum, and the blue involucre under the capitulate 

 umbels of species of Eryngium, in which even the stalk of the inflorescence is 

 of a bright blue colour. 



By the association of several or many flowers in an inflorescence, it is frequently 

 brought about that even small flowers are rendered sufficiently conspicuous. The 

 florets of the Compositae, for example, together form inflorescences that are visible 

 from afar, with the result that these plants receive more insect-visits than any 



G 2 



