448 THE AMERICAN NATURALIST. [Vol. XXXVII. 



pollinators are bees. " The flowers of a species of Trianosper- 

 ma in South Brazil are visited, according to Fritz Miiller, very 

 abundantly all day long' by Apis mcllifica and a species of Meli- 

 pona, although they are scentless, greenish, quite inconspicuous 

 and to a great extent hidden by the leaves." In this instance 

 as in some others the bees are probably guided by past expe- 

 rience in looking for the nectar. The large flowers of the culti- 

 vated Cucurbita are often wholly or partially concealed by the 



The stem-family, or line from which the other families of this 



Of the twenty-three northern species one is red and twenty-two 

 are blue. The flowers of Campanula are campanulate or rotate, 

 blue or white, and are visited by many Hymenoptera. Lobelia 

 has zygomorphic flowers which are usually blue or white. But 

 L. cardiualis, fn^tiis, sphudcus and hwrnis, have fiery red corol- 

 las adapted to humming-birds. There is no more brilliant red 

 color in the northern flora than that of the corolla of L. car- 

 dinalis. Phyteuma and Jasione are transition genera. 



At the head of the gamopetalous series stand the great 

 family of the Cojnpositae, which includes such familiar and 

 widely distributed plants as the thistle, aster, goldenrod, daisy 

 and dandelion. About 1000 genera and 12,000 species have 

 been described. Multitudes of these hardv weeds srrow lux- 



cosmopolitan, and have spread over both continents. The inflo- 

 rescence represents Nature's greatest triumph in flower building. 

 Intercrossing by insects, economy of time and material, a large 



large number of flowers in a head, an arrangement that also 

 permits insects to visit them very rapidly. In the goldenrod a 



hundred. The capituln 



