_Spiraea tomentosa_
_Flowers_--Pink or magenta, rarely white, very small, in dense,
pyramidal clusters. Calyx of 5 sepals; corolla of 5 rounded petals;
stamens, 20 to 60; usually 5 pistils, downy. _Stem:_ 2 to 3 ft. high,
erect, shrubby, simple, downy. _Leaves:_ Dark green above, covered with
whitish woolly hairs beneath; oval, saw-edged, 1 to 2 in. long.
_Preferred Habitat_--Low, moist ground, roadside ditches, swamps.
_Flowering Season_--July-September.
_Distribution_--Nova Scotia westward, and southward to Georgia and
Kansas.
An instant’s comparison shows the steeple bush to be closely related to
the fleecy, white meadow-sweet, often found growing near. The pink
spires, which bloom from the top downward, have pale brown tips where
the withered flowers are, toward the end of summer.
Why is the underside of the leaves so woolly? Not as a protection
against wingless insects crawling upward, that is certain; for such
could only benefit these tiny clustered flowers. Not against the sun’s
rays, for it is only the under surface that is coated. When the upper
leaf surface is hairy, we know that the plant is protected in this way
from perspiring too freely. Doubtless these leaves of the steeple bush,
like those of other plants that choose a similar habitat, have woolly
hairs beneath as an absorbent to protect their pores from clogging with
the vapors that must rise from the damp ground where the plant grows. If
these pores were filled with moisture from without, how could they
possibly throw off the waste of the plant? All plants are largely
dependent upon free perspiration for health, but especially those whose
roots, struck in wet ground, are constantly sending up moisture through
the stem and leaves.