THE ACANTHUS FAMILY, 2oi 



cultivated. The calyx is five-parted. The corolla- 

 tube is short, and two-lipped. There are only two 

 stamens, projecting forwards. There are about twenty 

 species, chiefly Eastern. 



Duvernoi'a. — D. Adhatodoi' des is a Natal shrub often 

 cultivated, and illustrates how the corolla has become 

 perfectly adapted to bear the weight of the large bee 

 which visits it, as will be seen by the accompanying 

 illustration.^ 



I. II. 



Fig. 80a. — Duvernoi'a. I. Flower. II. Ditto with bee. 



Looking at (I.) above (supposing we know nothing 

 of insect visitors), one might ask — For what use is this 

 great irregularity of the corolla ? Why and how has 

 it come into existence ? And no answer is forth- 

 coming. Now, turning to (II.), we at once see a use. 

 The weight of the bee must be very great ; and the 

 curious shape of the lip with its side ridges is evidently 



^ From a paper by Mrs. Barber, Joiirn. Lin. Soc, vol. xi. p. 467. 



