RECEPTION OF FLOWER-SEEKING ANIMALS AT THE FLOWER. 



229 



lutely, but the upper and under halves are quite different. In this respect they 



are comparable to the face of a man, to the head of a vertebrate, or to the body 



of an insect— indeed many of these flowers resemble the heads of animals or flies, 



butterflies, spiders, &c. (cf. Oncidium 



Papilio and Stanhopea JDevoniensis, 



Plate XIII. p. 224, and Ophrys cornuta 



and Galeopsis grandiflora, figs. 257 ^ 



and 257^). Flowers exhibiting this 



kind of bi-lateral symmetry are known 



as ZygomorpMo. Undoubtedly this 



Zygomorphy of laterally-directed flow- 

 ers is connected with the formation of 



a landing-stage suitable for particular 



insects to alight upon. The Zygomorphy 



of Gorydalis is peculiar, as noted at the 



end of the last paragraph but one. 



In flowers whose opening is directed 



upwards, quite apart from its nature, 



whether it be the mouth of a narrow 



tube or the broad edge of an expanded 



plate, Zygomorphy is superfluous. Such 



flowers are constructed symmetrically 



on every side. Their petals are placed 



like the spokes of a wheel or the rays 



of a star; they have been termed 



Actinomorphic. 



Such flowers, directed upwards, pre- 

 sent a landing-stage to insects either at 

 the periphery or at the centre. Humble- 

 bees which visit the erect, open flowers 

 of Gentians (Gentiana asclepiadea, 

 pannonicce, Pneumonanthe, punctata) 

 alight first on the edge of the corolla, 

 and then climb down into the wide 

 tube, disappearing whilst they suck the 

 honey. In the majority of cases, how- 

 ever, the edge of the corolla is so ex- 

 tremely delicate and flimsy that heavy 

 insects, such as beetles, would not be adequately supported, but would bend the 

 corolla right down on to the middle of the flower. Thus, in such flowers we fre- 

 quently find an expanded disc-like or star-shaped stigma which forms an admirable 

 platform, as in the flowers of Tulipa, Paris, Opuntia, Papaver, and Argevnone 

 {cf. fig. 243, p. 168). In Roses, Buttercups, and Anemones a large number of carpels 



Fig. 259. — Wood Anemone {Anemone nemorosa). 



1 Complete plant ; natural size. 2 xhe collection of carpels 

 from the centre of the ilower; magnified. 



