146 INTRODUCTION TO BOTANY 
of the evening primroses, honeysuckles, and Jimson weeds 
(fig. 131). The nectar from such flowers can best be reached 
by insects with a very long proboscis, like that of the butter- 
flies or the hawk moths (fig. 131). Many flowers with long 
corolla tubes are also visited by humming birds. 
Red-clover flowers are pollinated 
mainly by bumblebees. What effect 
Fie. 180. A, head of cab- 
bage butterfly ; B, head 
of honeybee 
a, antenne ; pr, proboscis, 
or sucking organ. The pro- 
boscis of the butterfly is Fic.131. Pollination of flower of Jimson 
represented as coiled into 
4 spiral. Both aomenthat weed (Datura) by a hawk moth 
magnified. After Behrens The nectar is inaccessible to ordinary insects 
upon the crop of clover seed have field mice, which destroy 
the nests of bumblebees? How would red clover thrive if 
introduced into a country where there were no bumblebees ? 
139. The arum ; a pitfall flower cluster. Our common jack- 
in-the-pulpit is the most familiar American member of the 
great (mostly tropical) Arum family. The over-arching hood 
and the tube from which it springs inclose a club-shaped 
axis on which are borne many inconspicuous flowers. Great 
