FLOWERS AND THEIR WORK. 245 



starting from the simple "hypogynous" condition, the formation of a 

 "perigynous" or "epigynous" flower, of a " gamophyllous " perianth, 

 of a " gamosepalous " calyx, of a " gamopetalous " corolla, of "epipeta- 

 lous" stamens, etc., in short, all the cases of '"cohesion" and "adhe- 

 sion " are due to the growth of the receptacle during the flower's 

 development, and that all these conditions in the mature flower are 

 due to differences in the extent of this growth. It is important to 

 remember this, as the various terms in current use tend to obscure the 

 facts of development, and even to imply that actual "fusion" occurs 

 after the various flower-parts have been developed. 



272. Protection against Rain. The flowers already 

 mentioned show examples of the various ways in which the 

 pollen may be protected against rain. Pollen-grains, like 

 seeds, are much less resistant to extremes of temperature and 

 to drying when once they have been moistened and have 

 begun in consequence to germinate. In some flowers, 

 especially those whose pollen is exposed to rain when the 

 flower opens, the pollen-grains are not readily wetted, having 

 a covering of wax or of spines, etc. In most cases, however, 

 the grains lose their power to germinate if wetted and then 

 allowed to dry. 



Many flowers protect the pollen by their horizontal or 

 drooping position, e.g. Heaths, Bluebell, Lily of the Valley, 

 Solomon's Seal, Violet, Daffodil. In some cases the flower 

 closes up at night or in bad weather, e.g. Wood Sorrel, 

 Tulip, Crocus, Lesser Celandine, Scarlet Pimpernel (in which 

 self-pollination often occurs in the closed-up flower, by 

 the stamens touching the stigma), and the same kind of 

 closing is effected in the flower-heads of many Composites by 

 the movements of the flowers and bracts. In Iris (Fig. 108) 

 the large petaloid stigmas cover the stamens, while in Orchis 

 (Art. 312) the single stamen is covered by a hood formed 

 by one of the sepals and two of the petals. Find other 

 examples. 



273. Wind-Pollinated Flowers. Many flowers which 

 contain no honey are visited for pollen by insects, attracted 

 by the colours or scents of these " pollen-flowers." Several 

 examples have been mentioned. This leads to the con- 

 sideration of flowers which have neither honey, scent, nor 

 conspicuous colours, and which are seldom or never visited 



