174 ELEMENTS OF BOTANY 
or by appendages.1. Those flowers which have one or 
more sepals or petals prolonged into spurs, like the nastur- 
tium and the columbine, are inaccessible to most insects 
except those which have a tongue or a sucking-tube long 
Fic. 180. A Sphinx Moth with a Long Sucking-Tube. 
enough to reach to the nectary at the bottom of the spur. 
The large sphinx moth, shown in Fig. 130, which is a com- 
mon visitor to the flowers of the evening primrose, is an 
example of an insect especially adapted to reach deep 
into long tubular flowers. 
207. Bird-Pollinated -Flowers. —Some flowers with very 
long tubular corollas depend entirely upon birds to carry 
their pollen for them. Among garden flowers the gladi- 
olus, the scarlet salvia, and the trumpet honeysuckle are 
largely dependent upon humming-birds for their pollina- 
tion. The wild balsam or jewel-weed and the trumpet- 
creeper are also favorite flowers of the humming-bird. 
208. Prevention of Self-Fertilization. — Dicecious flowers 
are of course quite incapable of self-pollination. Pistillate 
1 On protection of pollen, see Kerner and Oliver, Vol. U, pp. 95-109. 
