390 



BRITISH FLOWERING PLANTS 



CHAP. 



were probably the Papyrus [Papyrus antiquorum a 

 member of the Cyperacese), which would be plentiful in 

 the river Nile. 



Sparganium 



Protogynous, monoecious wind flowers, in globular 

 heads. We have three species. One, S. ramosum, has 

 the inflorescence branched ; in the other two it is 

 simple — one, S. simplex, has short, the other, S. 

 minimum, long styles. 



AEOIDE^ 



Arum 



Monoecious, protogynous fly-trap flowers. The spike 

 is half concealed in the large leaf or spathe, only the 

 purplish or yellow club-shaped top ap- 

 pearing. The spike supports a number 

 of pistils (Fig. 319, p) near the base, and 

 of anthers {a) somewhat higher. Now 

 in this case nothing would at first sight 

 seem easier or more natural than that 

 the pollen from the anthers should fall 

 on, and fertilise, the pistils. This, how- 

 ever, is not what occurs. The stigmas 

 mature before the anthers, and by the 

 time the pollen is shed, have become 

 incapable of fertilisation. It is impos- 

 sible, therefore, that the plant should 

 fertilise itself. Nor can the pollen be 

 carried by wind. When it is shed it 

 drops to the bottom of the tube, where 

 it is so effectually sheltered that nothing 

 short of a hurricane could dislodge it ; 

 and although Arum is common enough, 

 still the chances against any of the pollen so dislodged 

 being blown into the tube of another plant would be 

 immense. 



Fio. 319.— Diagram- 

 matic section of 

 inflorescence of 

 Arum, a, anthers ; 

 A, hairs ; p, pistils. 



