gradually lengthened spike keeps up an uninterrupted succession
of bloom for months, more than ample provision is made for the
perpetuation of the race - a necessity to any plant that refuses
to thrive unless it stands in water. Ponds and streams have an
unpleasant habit of drying up in summer, and often the pickerel
weed looks as brown as a bulrush where it is stranded in the
baked mud in August. When seed falls on such ground, if indeed it
germinates at all, the young plant naturally withers away.

In the Bulletin of the Torrey Botanical Club, Mr. W. H. Leggett,
who made a careful study of the flower, tells that three forms
occur, not on the same, but on different plants, being even more
distinctly trimorphic than the purple Loosestrife. As these
flowers set no seed without insects' aid, the provisions made to
secure the greatest benefit from their visits are marvelous. Of
the three kinds of blossoms, one raises its stigma on a long
style reaching to the top of the flower; a second form lifts its
stigma only halfway up, and the third keeps its stigma in the
bottom of the tube. Now, there are two sets of stamens, three in
each set bearing pollen grains of different size and value.
Whenever the stigma is high, the two sets of stamens keep out of
its way by occupying the lowest and middle positions, or just
where the stigmas occur in the two other forms; or, let us say,
whenever the stigma is in one of the three positions, the
different sets of stamens occupy the other two. In a long series
of experiments on flowers occurring in two and three forms -
dimorphic and trimorphic - Darwin proved that perfect fertility
can be obtained only when the stigma in each form is pollenized
with grains carried from the stamens of a corresponding height.
For example, a bee on entering the flower must get his abdomen