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 iiowers resemble the heads of animals or flies, 

 butterflies, spiders, &c. (cf. OncidiuTn 

 Papilio and Stanhopea Bevoniensis, 

 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 Zygomorphic. 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 

 AcUnomorphic. 



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, 

 pannoniccB, Pnewmonanthe, 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 Argemone 

 {of. 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 The collection of carpels 

 from the centre of the flower ; magnified. 



