112 



PROTECTION OF POLLEN. 



of wind causes the drops to roll off the limb of the corolla, or else they are 

 got rid of by evaporation; in either case, the flower becomes once more accessible 

 to insects. 



In none of the instances hitherto described does any change take place in 

 the relative positions of the foliage-leaves, petals, or petaloid stigmas, whereby 

 the pollen shall be the better protected. On the other hand, there is a long 

 list of plants wherein the protection of the pollen is effected exclusively by 

 means of changes in the position of some one or other of the leaves in question. 

 This occurs especially in all those species which, like the forms last mentioned. 



Fig. 222.— Protection of Pollen from Rain. 



' Flower of E^chschoUzia Cali/ornica opened in the sunshine. 2 The same closed in wet weather. 8 p'loral capitulum of 

 H ceracium JHlonella, closed. * Single ilower of the same plant. ^ Capitnlum of the same, open. 6 Longitudinal section 

 througli a closed capitulum of Catananche cosndea. ' Single flower taken from the capitulum in the last stage of 

 flowering. 8 Portion of inflorescence of Hydrangea querci/olia. 8 Young closed flower of £i-antlns hiemalis. lo Old 

 closed flower of the same. 



have the mouths of their flowers exposed to the incidence of rain, or unshielded, 

 so that radiation is not diminished and dew is formed, but, unlike them, exhibit 

 no sufiicient constriction of the tubular part of the corolla to prevent drops of 

 water from falling into the flowers. Such unconstricted, cup-shaped, urceolate, 

 infundibular, or tubular flowers would, if upright, constitute regular rain-collectors, 

 and the water would at once saturate the pollen within the flowers. If flowers 

 of the kind close up temporarily and keep their petals or involucral leaves 

 arched over the interior so long as there is any risk of water collecting there, 

 the requisite security from inundation is attained by very simple means. As 

 a matter of fact, protection of pollen is effected in numerous cases by the 

 closing of flowers. Examples of this are aflbrded by the flowei-s of Meadow 

 Saffi-on, Sternbergias, and Crocuses {Colchicum, Sternbergia, Crocus, cf. fig. 223), 



