Wednesday, January 30, 2013

Don't Touch Me!

There are two related species of native wildflowers known as Touch-me-nots:  the Spotted Touch-me-not (Impatiens capensis) and the Pale Touch-me-not (Impatiens pallida).  For what reason would a plant be called a touch-me-not?  If you ask a group of elementary students about the name, you will probably get a list similar to this:

  • The plant is poisonous to people.
  • The plant is poisonous to animals.
  • The plant has thorns.
  • The plant can cause an allergic reaction.
  • The plant is dangerous in some other way.
  • The plant is poisonous to other plants.
  • The plant will die if touched.
So which of these is the true reason behind the name?  Or is it a different reason entirely?

Sometimes called Jewelweeds, the Spotted and Pale Touch-me-nots are both summer wildflowers that live in wetlands and wet woodlands surrounded by many other species. 

Both plants grow up to 3 to 5 feet tall.  Neither plant has thorns.  Instead, both plants have soft succulent stems and leaves which are eaten by deer and other herbivores.  Both species of plants are quite hardy and can tolerate repeated browsing by animals.

The sap from these soft plants can be used to counteract the itching and pain caused by stinging nettles and poison ivy.  So rather than causing allergic reactions, the plant helps treat them.  In fact, touch-me-not plants often grow in the same locations as nettles.

The only real difference between the two species is the color of their flowers. The Spotted Touch-me-not has orange flowers with reddish-brown spots.

Spotted Touch-me-not

The Pale (or Yellow) Touch-me-not has pale yellow flowers.

Pale Touch-me-not

The tubular flowers of both species are popular nectar sources for bees and especially for hummingbirds.

The plants are sometimes called Jewelweed for the way that water beads up on their leaves, giving  a jeweled appearance.

Dew covered "jewelweed"

So if the plants do not have thorns, are not poisonous, don't cause allergic reactions, and live in harmony with other plants and some animals; why are they called "touch-me-nots"?  The answer is in their seeds.  No, the seeds are not poisonous.  The answer is much more fun.

The seeds are encased in 1/2 to 1 inch long pods.  When the ripe pods are touched they explode.  There is no bang.  You will not lose a finger from grabbing one.  Instead, the pod is lined with several fibers that are held under tension.  One the pod ripens, the membrane holding the tension on the fibers weakens until eventually any touch, even a jarring from the wind, causes the membrane to break and the fibers to contract.  When the fibers contract the seeds are flung in multiple directions.

This adaptation is the plants method of seed dispersal.  It ensures that seeds do not fall directly underneath their parent plant.  It might also be a method that the plant uses to prevent its ripe seeds from being devoured by birds and other animals.  A bird that grabs an exploding seedpod with its beak may think twice before doing so a second time.  A person, on the other hand, having made a seed pod explode once will usually want to make it happen again and again.

Spotted Touch-me-not flower and seed pods in various stages of ripeness

Ripe seedpod- the fibers are clearly visible and the seeds can be seen bulging the sides of the pod


  1. Spotted Touch-Me Nots, one of my favorite wild flowers!

  2. Wow, how interesting! We just saw some of the spotted touch me nots at our favorite walking site- a boardwalk through the woods to Ford Lake.

    1. I hope you took the time to pinch some of the pods and help the plant sow its seeds.