ARUMS. 281 



the dark green arrow-shaped lea\'es. TheA' consist of a 

 ckib-shaped spadix bearing small inconspicuous flowers, 

 and a dark-brown spathe, striped with wliite, wliich envel- 

 opes the spadix. Tliis spatlie is not a floral en^'elope 

 but a bract. It forms a tube terminating in a flap which 

 curves over like a helmet. The bare end of the spadix 

 is also brown and protrudes from the tube. TJie un- 

 pleasant smell emitted b\ tliis inflorescence attracts small 

 flies and midges; these cra\'\-l down the spadix and rub 

 against the flo\vers, thus effecting pollination. The spadix 

 bears both staminate and carpellar\' llouers. As the 

 stigmas of the latter come to maturity before the staminate 

 flowers discharge their pollen, they are generally fertilised 

 b)- pollen which the insects bring from other flowers, 

 ^rhe Italian Arum (^iriiiii I'talicuiii), which is commonly 

 met with here in the spring, is pollinated in the same 

 w'lw. Its arrow-shaped leaves (Fig. p. 41) are much 

 larger and more pointed than those of the ^\risarum. The 

 venation is of a lighter preen than the rest of the leaf, 

 so that it is easy to distinguish these two plants even 

 when not in flower. A. italicmn flowers later than Arisarum. 

 Its inflorescence resembles that of the Calla aetJiiopica 

 so commonly grown in pots at home. The thickened 

 end of tlie ^■ellow spadix protrudes from a large wliite 

 spathe. In this flower it is not so much the smell, as 

 the conspicuous \ellow colour of the spadix and the 

 ^\•armth given out b^' it that attracts the midges upon 

 which the pollination depends. The temperature begins 

 to rise in the morning and reaches its maximum between 

 six and eight in the evening. A spadi.x will then attain 



