PROTECTION OF POLLEN. 



121 



'.Ipina, A. carniolica, &c.), it is the stalks of the umbels, and in some Cruciferous 

 ilants (e.g. Draba aizoides, Arabis Turrita, Sisymbrium Thalianum), the axes 

 if the racemes. The above-mentioned Scabious and Composites exhibit a periodic 

 aversion of the entire inflorescence in consequence of the inflection of the axis, 

 ind the radiating ligulate florets set round the margin of the capitulum serve 

 o shelter the pollen of the central florets. Similarly in the Umbellifers named, 

 ihe involucres of the separate umbels, being comparartively large, act in the same 

 vay. The fact is also worth notice that in some Willow-herbs (e.g. Epilobium 



V,i 



\^ 



^,>^ 





Fig. 225. — i:'rotectiuii of Pollen. 



Flowers of the Herb-Robert (Geranium Robertiamim) in the daytime ; the pedicels erect. 2 The same plant with its flowers 

 pendent on curved pedicels, the position assumed during the night and in wet weather. 3 Bell-flower {Campanxda 

 patula) by day; the flower on erect pedicel. ■* Flower of the same plant inverted for the night or for wet weather, the 

 pedicel being curved, s Capitulum of a Scabious (Scabiasa lucida) in the daytime ; the peduncle erect. ^ Capitulum of 

 the same plant at night or during rain, the peduncle curved and the capitulum inverted. 



iirsutum,, E. Tnontanum, E. roseum), the flower-stalks themselves do not bend, 

 3ut the long stalk-like inferior ovaries curve downward and straighten out 

 igain, periodically causing the flowers, which are of a flat salver shape, to 

 iltemate between a pendent and an erect position. The inflection of flower- 

 italks, or, of their substitutes, the ovaries, ceases as soon as the pollen of the 

 lowers concerned has been removed by one means or another, and a shelter for 

 t is no longer needful. The flower-stalks of Saxifraga Huetiana only con- 

 iinue to bend so long as the anthers in the flowers they support are covered 

 vith pollen, and the long ovaries of the Willow-herbs mentioned above 

 )nly curve towards the earth on two successive evenings; the third evening, 



