Early summer is the best time of year for wildflowers all across the northland. There are many spectacular varieties of wildflowers dotting the landscape such as the amazing orchids, lovely lilies, and bright and cheerful daisies. But there is one wildflower that really catches my attention. Not for its stunning beauty, but rather for its amazing and highly unique flowers. This wonderful wildflower is the Common Milkweed (Asclepias syriaca).
The Common Milkweed is a native plant that grows in a wide variety of habitats including open fields, along roads, prairies, and open woodlands. Chances are it’s growing in your garden or the part of your yard that you don’t mow and have left to go ‘wild’.
It is not a very impressive wildflower, as far as wildflowers go. It’s a single stemmed plant, standing 2-3 feet tall with pairs of large oval leaves oppositely attached. The leaves bleed a white milky sap when broken as does the rest of the plant.
This plant has several large round clusters of cream to pink colored flowers. Now here is the unique part that I mentioned earlier. The flowers are highly fragrant and attract a lot of insects. When an insect arrives it is greeted with a flower with five petals that have folded back to form individual cups which contain the sweet nectar. Each nectar cup has a little horn coming out of the center and curves in toward the center of the flower. The effect of these horns is to limit where a visiting insect can place its feet. In addition all the surfaces on the flower are smooth and slippery making it very difficult for insects to hold on long enough to get a sip of nectar.
The only way an insect can keep from slipping is to place its feet into highly specialized and strategically placed slits between the nectar cups. There are five such slits on each flower. As the insect tries to take hold, it moves its feet from one end of the slit to the other. Waiting inside each slit is a tiny sticky black pad. Attached to the sticky pad is a sac of pollen. When the insect pulls its legs free to leave the flower, the sticky pad adheres to the insect’s leg like a saddle bag. Sometimes the insects that visit the milkweed flower are not strong enough to pull its leg out of the slit and they are trapped indefinitely.
The pollen of the milkweed is not powdery like ordinary pollen. Instead it’s waxy and sticks together in a tiny pear-shaped package. When the pollen packets are carried to the next milkweed flower, the insect’s leg needs to slip up and down the slit again so the pollen packet can break off and remain in the slit, completing the next step in the pollination process. Getting the pollen packets into the receptive flower is not very easy and that is way this plant produces large clusters of flowers because only one or two become successfully pollinated.
Once the pollen packets are inside the slit, the pollen grains still need to reach the ovules at the bottom of the pistils. At the back of the slit there is a sugary liquid in which pollen grains can grow. The pollen grains grow tubes that reach down into the stalk of the pistil and reach for the ovule. Once the tubes reach the ovules, fertilization is complete and seeds start to develop. In autumn the large seed pod opens to release hundreds of seeds which are carried away each seed on the wind by tufts of silky hairs that are attached to the seeds and act like parachutes.
The Common Milkweed plant has been very useful in the past also. People have used the silky seed hairs to stuff pillows, dolls or pin cushions. During World War II milkweed seed pods were collected and the silky hairs were used in life preservers. The waxy hollow silk floats. Three and a half pounds of silky hairs could kept a man afloat for three days. In addition, the milky sap that oozes from the damaged plant tissue was used like rubber cement when dried. The milky sap contains cardiac glycoside (a digitalis-like compound) that has powerful effects on the cardiovascular system. It has been used in folk medicine for hundreds of years.
All of this makes the Common Milkweed one of my favorite northland wildflowers.
Until next time…