from Premature Dislodgment or Moisture. 433 



placed about halfway up the corolla and closing it completely, 

 so as to shelter the stamens and leave only a narrow passage 

 for insects. In the periwinkles, oleanders, &c. the anthers 

 bear at their summits a sort of spoon-shaped prolongation, and 

 the style is surrounded by a collar of long stiff hairs ; the 

 junction of these two organs forms a perfect roof above the 

 pollen. In the Composite the tube formed by the union of 

 the anthers, in the interior of which is the pollen, shelters it 

 until the moment when insects come to collect it. 



Frequently the protective shelter comes from the perianth. 

 A great number of plants have a portion of the corolla developed 

 into the form of a regular roof placed over the anthers. This 

 peculiarity of organization is characteristic of some very im- 

 portant families (such as the Labiatge, Scrophulariacese, Oro- 

 bancheai, Gesneriaceas, Utricularia?, PolygaleEe, Violaceee, 

 many Papilionacese, and some Ranunculaceaj). 



In other cases the upper part of the lobes of the corolla 

 remains united during the first portion of the flowering, thus 

 protecting the stamens and the style (Phyteuma) ; or, as in 

 Trollius, the petals, which are strongly concave within, join 

 at the top of the flower. In other cases, again, the tube of the 

 corolla which encloses the anthers is so narrow that water 

 cannot penetrate into it, the air finding no means of exit and 

 remaining enclosed in the form of a bubble, which keeps the 

 pollen dry (Androsace, Verbena) ; or, what is still more fre- 

 quent, the entrance of the tube is closed by hairs, scales, &c. 



The spatke in many Aro'ideae, the bracts of certain Musacese, 

 and the leaves of the lime tree extend over the flower or the 

 inflorescence like an umbrella. 



When no part of the flower is constructed so as to be able 

 to shelter the stamens from the weather, the desired result is 

 obtained either by periodical movements of the perianth or by 

 curvatures of the axis. 



In the first category we find, in the first place, all the so- 

 called ephemeral flowers, the opening of which lasts only 

 one day {Villarsia, Tradescantia , Convolvulus tricolor, 

 Tigridia pavonia, and many others). The anthers open and 

 allow the pollen to escape in the bud, which on its part opens 

 only during the hottest part of the day, when the sun is shining, 

 and the insects, buzzing about everywhere, are ready to effect 

 fecundation. Those flowers which present a similar structure, 

 but of which the anthesis lasts several days, are governed by 

 similar laws ; they close during the cooler hours, when the dew 

 might injure the pollen, and also during rainy weather and 

 when little life is about. Some of them particularly affect 

 twilight and evening ; they only open a little after the setting 



