COLOURS OF FLOWERS AS A MEANS OF ATTRACTING ANIMALS. 183 



coloured yellow, white, or red on the inside only, while the outer side is green. 

 Those, for example, of Oagea are yellow on the inside only whilst the outside is 

 green. When these flowers are closed they do not strike the eye; only when 

 opened in the sunlight does the yellow star show up from the background. The 

 same thing may be said of the flowers of the Star of Bethlehem (Ornithogalura), 

 of the Lesser Celandine (Ranunculus Ficaria), of the Pimpernel (Anagallis), of 

 the Venus's Looking-glass (Specularia) and of many other plants. 



In some instances where the petals have been transformed into nectaries, or 

 have assumed some other function, which would not easily allow of their developing 

 brightly-coloured surfaces, the duty of alluring the animals is performed by the 

 sepals. These are then not green, but are coloured white, yellow, red, blue, violet, 

 or brown, as, for instance, those of the Christmas Rose and of the white Wood 

 Anemone {Helleborus niger, Anemone nemorosa), of the Globe-flower and Winter 

 Aconite {Trollius, Eranihis), of the Atragene and of the Monkshood (Atragene 

 alpina, Aconitum Napellus), of the Pasque-flower and of the Marsh Cinquefoil 

 {Pulsatilla pratensis, Gomarum palustre). And of course the features noted above 

 in the case of the petals is repeated in these flowers — the outer side of the calyx 

 is brightly coloured in the hanging bells of the Marsh Cinquefoil, but the inner 

 side in the star-shaped, open flowers of the Pasque-flower. 



Nor do the stamens, in comparison with the corolla, calyx, or perianth, fre- 

 quently serve as attractive organs to animals in virtue of peculiar colouring. In 

 Northern and Central Europe we notice the Willows — destitute of perianth-leaves 

 — rendered conspicuous from afar by their numerous, crowded stamens with red 

 or yellow anthers. In other cases the flowers are conspicuous in virtue of their 

 brightly-coloured stamen-filaments — white, purple, red, or yellow — as in certain 

 Ranunculacese, e.g. Actcea, Gimicifuga, and Thalictrum, still more in the Acacias 

 of Australia, and in the genera Gallistemon and Metrosideros belonging to the 

 Myrtacese, in the Japanese Bocconia, as well as in several species of yEsculus (e.g. 

 ^. macrostachya). The flower-spikes of the North American Pachysandra, which 

 trail along the ground, yet stand out from the dark environment because the 

 filaments are dazzling white. In several Asiatic Steppe-plants, viz. in species of 

 Halimocnemis (see figs. 252 ^^ and 252 ^^), a bladder-like appendage rises above 

 each anther, and is coloured sulphur-yellow, violet, bright or dark red, and thus 

 stands out brilliantly from the gray-green surroundings and might easily be 

 mistaken at first sight for a petal. 



It often happens that the bracts which subtend and enfold the flowers rather 

 than the flowers themselves attract attention by the contrast of their colours with 

 the surrounding green. Numerous examples are furnished by the Cornel (e.g. 

 Cornus florida and Suecica; see fig. 252 ^^), the Myrtaceas (Genetyllis tulipifera), 

 the Umbelliferse (Astrantia, Bupleurum, Smyrnium, Eryngium alpinum), the 

 Labiatese (Nepeta reticulata, Salvia splendens), Compositse (Girsium spinosissi- 

 mum, GvMphalium Leontopodium, Xeranthemum, annuum, Garlina acaulis; see 

 p. 117), the Spurges (Euphorbia polychroma, splendens, variegata), the Aroids 



