Meet The Compass Plant

Few prairie plants stand out more than the compass plant (Silphium laciniatum). With its uniquely lobed leaves and a flower stalk that rises well above the rest of the vegetation, it is nearly impossible to miss. It is also quite easy to identify. Seeing a population in full bloom is truly a sight to behold but the ecology of this species makes appreciating its splendor all the more enjoyable. Today I would like to introduce you to this wonderful member of the aster family.

Any discussion about this species inevitably turns to its common name. Why compass plant? It all has to do with those lovely lobed leaves. When they first develop, the leaves of the compass plant are arranged randomly. However, within 2 to 3 weeks, the leaves will orient themselves so that their flat surfaces face east and west. They also stand vertically. This is such a reliable feature of the plant that past generations have learned to use it as a reliable way in which to orient themselves.

Of course, helping humans find their way is not why this feature evolved. The answer to their orientation has to do with surviving in the open habitats in which they grow. Anyone who has ever spent time hiking around in prairie-like habitats will tell you that the sun can be punishing and temperatures get hot. What's more, the range of this species overlaps with much of the rain shadow produced by the Rocky Mountains meaning water can often be in short supply.

By orienting their leaves in a vertical position with the flat surfaces face east and west, the plants are able to maximize their carbon gain as well as their water use efficiency. At the same time, the vertical orientation limits the amount of direct solar radiation hitting the leaf. In essence, compass plant leaf orientation has evolved in response to the stresses of their environment. Research has shown that the sun's position in early morning is the stimulus that the plant cues in on during leaf growth.

Aside from its fascinating biology, the compass plant is also ecologically important. Myriad pollinators visit its large composite flowers and many different species of birds feed on their seeds. However, it is the insect community supported by the compass plant that is most impressive. Surveys have shown that nearly 80 different species of insect can be found living on or in it stems. Many of these are gall making wasps and their respective parasitoids. With individual plants producing up to 12 stems each, these numbers soon become overwhelming. Needless to say, this is one of the cornerstone plant species anywhere it grows naturally.

Photo Credit: [1]

Further Reading: [1] [2] [3]

 

Pasqueflower

The true harbinger of spring on the northern prairies of North America, Europe, China and Russia is none other than the pasqueflower (Anemone patens). It bursts forth from the ground with its fuzzy, dissected leaves often before all of the snow has had a chance to melt. It then proceeds to put on quite a show with flowers that range the spectrum from white to deep purple. Everything about this plant is adapted to take advantage of early spring before competing vegetation gets the upper hand. 

One of the coolest aspects of pasqueflower life are its flowers. These parabolic beauties need to be able to function despite the constant risk of freezing temperatures. To stay warm, the flowers will actually track the sun's movement across the sky. In this way, they are able to absorb solar radiation all day. What's more, the parabolic shape and reflective surface of the petals serves to bounce solar radiation towards the center, thus amplifying the amount of heat. Pasqueflower blooms can actually maintain a daytime flower temperature upwards of 18 degrees Celsius above ambient temperatures, not only providing a warm spot for pollinators but also increasing the rate at which the seeds develop. 

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The seeds themselves are quite interesting structures as well. Getting into the soil can be a difficult task when your neighbors are thick prairie grasses. Pasqueflowers get around this problem by producing seeds that literally bury themselves. Each seed is attached to an awn that is made up of alternating strands of tissue. Each strand varies in its ability to absorb moisture. As spring rains come and go, the awns will twist and turn with the resulting effect of drilling the seeds directly into the ground. 

Once the surrounding vegetation begins to wake up, pasqueflower is already getting ready to go dormant. By mid-July it is usually back underground. It is a prime example of how breaking dormancy early can help a plant beat the competition of the growing season. Also, pasqueflower can be very long lived, with individuals persisting upwards of 50 years in a given location. Not only is this plant is both hardy and beautiful, it also has the added ecological benefit of providing early prairie pollinators with a much needed boost of energy. 

Photo Credit: [1] [2]

Further Reading: [1] [2]

 

A Mallow Called Kankakee

In the spirit of this week's podcast I would like to take a look at a very special plant. It happens to be one of the rarest plant species in the lower 48. What may surprise you even more is that this species is endemic to a small island in the middle of the Kankakee River of Illinois called Langham Island. I am, of course, talking about the Kankakee mallow (Iliamna remota).

It is strange to think of something endemic to a 20 acre island in the midwest but that seems to be the case. Though disjunct populations have been located in Indiana, experts feel that these were the result of early attempts at saving this species from extinction. In fact, the rarity of this plant was realized quite early on. A series of taxonomic revisions made it so that by the early 1920's, botanists knew that Iliamna remota was distinct from similar species such as liamna rivularis and Iliamna corei.

Despite its uniqueness, there doesn't seem to be too many explanations as to why this species is limited to Langham Island. Perhaps our recent glacial past has something to do with it. It very well could also be due to the fact that roughly 80% of Illinois has been converted to farmland. It is also due, in part, to the lack of life-giving fires that the prairies so desperately need. Indeed, after decades of attention, Langham Island and the Kankakee mallow seemed to have faded from the spotlight.

In 1981, botanists realized that most of the plants on the island had disappeared. Only 109 individuals remained and no seedlings were found. It was starting to look like this species was doomed to extinction. Growing up in their place were thick stands of Japanese honeysuckle and multiflora rose. Luckily a handful of concerned biologists decided to light some fires. Wherever the fires burned away the invasive competition, seedlings began to emerge. Close inspection would reveal that these were the next generation of Kanakakee mallow!

A missing piece of this biological puzzle had been restored. The mallow seeds were waiting in the soil for a fire to release them from the tyranny of these invaders. It would seem that the future of this species was a bright one. Sadly, another round of budget cuts coupled with a decrease in public interest had swept through the region. When a group of botanists again went looking for this species in the summer of 2014, they realized that, to their horror, history seemed to have repeated itself. Gone were the remaining populations of the Kankakee mallow. Honeysuckle and multiflora rose had returned with vengeance.

It was clear that if this species were to be saved, Langham Island would need more dedicated attention. Thus the Friends of Langham Island was born. Since then, brush cutting and controlled burns have meant that the Kankakee mallow has once again rose from the ashes, literally. Ongoing attention from a concerned group of citizens may be the only means left at saving this endangered plant.

Photo Credit: Prairie Moon Nursery

Further Reading:
www.habitat2030.org

Check out The Brain Scoop's video about this plant

Listen to a podcast episode dedicated to the restoration of these species' habitat