398 THE ARALES 



is admirably adapted to the aquatic habit of these plants and 

 readily floats in the water, owing to the spongy outer tissues, and 

 so bring abouts the distribution of the seeds. The jack-in-the- 

 pulpit has a surer method for effecting a crossing, since the 

 sporophylls are usually borne on separate spadices. You will often 

 find, however, spadices with a few stamens situated just above 

 the pistillate flowers. The flowers are very simple, consisting of 

 a single naked pistil or of four nearly sessile stamens (Fig. 286, 

 C-D) . The fruit is a shining bright red berry. 



In some of the tropical genera the insects are held in the 

 spathe by hairs that extend obliquely downwards, thus permit- 

 ting the entrance but blocking the exit of the insects until cross- 

 ing of the flowers has been efi^ected. In one of the species of 

 Arum there are two sets of hairs that divide the spathe into two 

 compartments containing respectively staminate and pistillate 

 flowers (Fig. 286, E). As soon as the spathe opens the insect 

 ladened with microspores from another flower makes his way to 

 the lower chamber, where the stigmas are in a receptive condi- 

 tion. Here he is held a prisioner and rubs the microspores upon 

 the stigmas as he wanders about in the compartment. When the 

 microspores in the upper chamber begin to discharge, the lower 

 set of hairs wither, giving him entrance to this chamber, where 

 he feeds upon the microspores and becomes covered with them. 

 Finally the upper set of hairs wither and he is free to leave the 

 spathe and repeat his work in another inflorescence. 



133. Liliales, the Lily Order. — The members of this order 

 comprise nearly 5,000 species that are widely distributed and 

 extensively cultivated for their showy flowers. We have now 

 reached a point in the evolution of the flower where it has become 

 perfect and the protective spathe of preceding orders is replaced 

 by a well-developed perianth. The floral axis also becomes short- 

 ened and we pass from the spiral series of flowers with a vari- 

 able number of organs to the cyclic flowers with a definite 

 number of organs arranged in whorls. In the lily order there 

 are five whorls of organs of three members each, the stamens 

 being arranged in two whorls. Note also that this crowding 

 usually results in the complete coherence of the carpels (Fig. 



