Story by Virginia Barlow | Illustrations by Adelaide Tyrol
JEWELWEED, Impatiens capensis
There used to be a patch of jewelweed
that brushed up against the screen of
our sleeping porch, and before the sun
was up, we would wake to the zipping
of hummingbirds getting an early nectar
breakfast from jewelweed’s speckled
orange blossoms. Sadly, grasses superseded that patch, but happily, jewelweed
is still abundant in the landscape.
Jewelweed’s annual growth from seed
is careless and exuberant. The leaves are
on the juicy side, a bit bluish, with long
petioles and toothed margins. Moist soil
is essential to jewelweeds. The hollow
stems depend on water to keep the walls
turgid, and the uncommon sight of
drooping jewelweed in drought conditions is sorrowful.
The whole watery plant is reduced to
a pulp quite easily, which is good for us
humans because the mashed up vegetation can be applied to skin after contact
with poison ivy to prevent a rash from
developing. It seems that jewelweed is not
as effective at this as soap, but how often
do you carry soap with you on a walk in
the woods? Jewelweed mash also eases
the itches of stinging nettle and insect
bites and is used to treat fungal infections
such as athlete’s foot.
The plant’s name seems to have come
from the rain or dew that beads up on
jewelweed’s leaves, making silvery, jewellike spheres that sparkle in the sun. This
effect, called “ultrahydrophobicity,” is best
known from the waxy leaves of lotus. In
jewelweed, it’s minute hairs that cause this
effect. Surface tension allows dirt to be
picked up by the droplets and rolled away,
cleaning the leaves. In addition, a dry leaf
is protected from algae or fungi.
Hummingbirds are among the most
important pollinators of the showy, inch-long flowers, but a patch of flowering
jewelweed doesn’t attract just hummingbirds. Many species of bees, some
wasps, and even some flies spread
jewelweed pollen in exchange for
the abundant nectar that’s hidden in the
curving “tail” of the flower.
When you touch an elongated seed-
pod, it explodes and curls into ribbons
that wiggle in your hand like live animals.
The pods have an inner layer that
shortens when wet and an outer layer that
expands when wet, creating a mouse-
trap-like structure that goes “bang” when
conditions are just right. This accounts
for another of the plant’s names, “touch-
me-not.” The exploding pods scatter the
seeds up to six feet from the parent plant.
I show this remarkable feat to children
whenever I can, but usually I am the one
who is most impressed.
The seeds from the showy, open flowers
are genetically varied and shoot out of
the growth zone of the parents, where
they might land in a slightly different
environment and expand the colony. In
addition to its showy orange blossoms,
jewelweed produces closed, or cleistogamous, flowers. These small, self-pollinating flowers never open, but they
do produce seeds. They are much less
expensive to produce: no petals, no
nectar, and they don’t have exploding
seed pods. Seeds from the closed flowers
fall directly to the ground and, being
clones, find themselves in the same place
where their parents were so successful.
Many other plants – grasses, beans and
violets among them – also make such
cheap flowers. Interestingly, seeds from
cleistogamous jewelweed flowers grow
into plants that have a higher percentage
of regular flowers. Both kinds of seeds
last only one year.
In sunlit, rich, moist soil, there are more
insect- and hummingbird-pollinated
flowers. It takes a lot of expensive nectar
to lure a hummingbird, but these pollinators do an excellent job of transporting
pollen to distant jewelweeds. The percentage of closed flowers increases with
less favorable conditions for growth, and
with deer browsing.
Jewelweed is perhaps the only native
plant that is able to smother and kill
garlic mustard, an aggressive, non-native
herbaceous plant. You might do good
while having fun by scattering jewelweed
seeds into a patch of garlic mustard.
Very few woodland wildflowers in our area are annuals, and it’s a wonder that any sane
plant would choose this approach. Being a biennial or perennial – storing up reserves
in one year and using this larder to get an early start the following spring – has been
overwhelmingly voted to be the surest way to survive. Yet some species succeed beautifully at packing all the steps into a single growing season.