234 The Romance of Wild Flowers 
the size of the pollen-grains, much as we found to be 
the case among the Primroses. The stamens are 
attached to the corolla as in the Gentians, but these 
differ in the fact that the anthers in discharging their 
pollen twist up into a spiral. The flowers do not 
appear to produce any honey, yet they are visited by 
butterflies and moths to whose long trunks the form 
of corolla-tube is adapted; they probably suck juices 
from the flower-tissue, as is done in Orchids and 
some other flowers. H. Miiller records the Humming- 
bird Hawk-moth, the Silver-Y moth, and the Yellow- 
Underwing among its visitors. 
More distinctly beautiful is the Bogbean, or 
Marsh Trefoil (Menyanthes trifoliata), which grows 
on the margins of woodland tarns and in bogg 
places. This bears stouter funnel-shaped flowers in 
racemes on a long stalk, the corolla pink without and 
white within, the inner surface of the five lobes 
fringed with fleshy filaments that serve to keep out 
creeping insects. Cross-fertilisation is insured by the 
flowers being of two forms: long-styled and short- 
styled. 
All the members of the Gentian family abound in 
a bitter principle, which has no doubt been developed 
for the protection of the plants against the browsing 
quadrupeds. 
