THE FLOWER AND THE BEE 



valuable honey-plants in North America, and its greenish 

 flowers yield annually thousands of pounds of a rich, aromatic 

 honey. The rock-maple in early spring, and the Boston ivy and 

 woodbine (Fig. 106) later in the season, are also valuable sources 

 of nectar to the bee-keeper. Large green flowers occur in 

 various exotic species of the nightshade family and in some 

 Brazilian orchids. They are strongly scented in the evening 

 and are attractive to nocturnal moths. 



Green flowers often contain other pigments besides chloro- 

 phyll, or leaf-green, as carrotin, tinging them various shades of 

 yellow, or green granules may be mingled with violet-colored 

 sap as in the dull-purple corolla of belladonna {Atropa bella- 

 donna), while the brownish color of the gooseberry is due to red- 

 cell sap and chlorophyll. 



Yellow Flowers 



The green pigment, or chlorophyll, in leaves is invariably 

 accompanied by two yeUow pigments, carrotin, so-called be- 

 cause it is common in the root of the carrot, and xanthophyll, or 

 leaf-yellow. Carrotin, to which most yellow flowers owe their 

 hue, is a solid substance, occurring in petals in small round 

 granules called plastids. It is very widely distributed in sea- 

 weeds, fungi, lichens, mosses, ferns, and the higher plants, in 

 autumn leaves and in fruits and seeds. It is insoluble in water, 

 but readily soluble in ether. The yellow plastids of flowers are 

 not always round, but are sometimes angular as in the garden- 

 nasturtium. In the tomato, asparagus, thorn-bush, and in 

 some species of rose, the plastids of the fruit are spindle-formed, 

 or irregular-shaped, and are fire-red, orange-red, or yellowish 

 red. In yellow leaves the plastids are round ; but in autumnal 

 leaves they occur in irregular masses. 



The scarlet poppy, tulip, and fire-red canna owe their colors 



228 



