PROTECTION OF POLLEN. 



113 



iich lift the cup-shaped limbs of their corollas above the ground in the 

 nng or late autumn, the Gentians of Alpine meadows and their allies of 

 3 Centaury genus (Erythrcea), a host of Bell - flowers with erect ' blossoms 

 avipamda glovierata, 0. spicata, C. Trachelium, Specularia Speculum, &c.), 

 e Peonies, Roses, Flaxes, Opuntias, Mammillarias and Mesembryanthc'mums, 

 merous species of the Star of Bethlehem, and Thorn-apple genera (e.g. Ornitho- 

 lum umbellatum, Mandragora vernalis, Datura Stramonium). The floating 

 •wers of the Water-lily (Nymphcea), and the large flowers which are borne 



Fig. 223.— Protection of Pollen. 



vers of Crocus multifidus. On the right, flowers open in the sunshine; on the left, flowers closed at night or in wet 

 weather. One of the three closed flowers has some of its perianth-leaves removed. 



the branches of Magnolias also belong to this group of forms. Throughout 

 s day when the sun is shining the floral cups or funnels of these plants are 

 ie open and often even expanded into stars, whilst swarms of insects hover 

 md them; but at dusk when the dew "falls" the petals close up again and 

 jrlap one another so as to form a case (cf. flg. 223) upon which any amount 

 dew may be deposited without affecting the interior of the cup. In damp 

 rainy weather these flowers do not as a rule open. Thus the period of their 

 ng closed coincides with a time when most honey-seeking insects are absent, 

 ring either gone to rest for the night, or retired to their hiding-places for 

 Iter from the wet. 

 It is a very interesting phenomenon that petals which close over the anthers 



Vol. II. 58 



