Tom's Blog

Tuesday, August 21, 2012

Cardinal flower and swamp thistle: wetland plants

Our wetland plants continue to thrive.

One of my favorites is cardinal flower (Lobelia cardinalis; C value of 7). Not too hard to know where that name came from!

In natural areas, this is a plant that you have little control of. It comes up where and when it chooses, and just as easily disappears. The reason? This species is monocarpic, which means that it may grow for one or more years in a vegetative state but after it finally flowers it dies. So even though it self-seeds, don't expect it to appear the same place next year. According to Cochrane and Iltis, this is one of the few plant species pollinated by the ruby-throated hummingbird. In fact, just before I took this picture, there was a hummer nearby. Unfortunately, I scared him away so I didn't get to watch the pollination process.We often have cardinal flowers in our garden at home. Again, we never know when or where they will appear. (This year we have none.)

Although the cardinal flower is a wetland plant, we first saw it at Pleasant Valley Conservancy in our White Oak Savanna. It was the year we cleared that savanna, and a single plant in full bloom appeared. Of course, we never saw it there again.

A related species is great blue lobelia (Lobelia siphilitica; C value of 5), which is also monocarpic but a lot more common than cardinal flower. We almost always see blue lobelia where we have cardinal flower (but not the other way around). This year we have lots of this lobelia.

The other wetland species that is in full bloom now is swamp thistle, Cirsium muticum; C value of 8). This is a very colorful species, with really intense purple-red flowers. Note that this is a native thistle and should NOT be pulled or dug. One way of recognizing this species: the flower buds are sticky when you touch them. Like most thistles, this species is a biennial, which means that once it flowers it dies. (The biennial is a special category of monocarpic.)

All three of these species are native to Pleasant Valley Conservancy, and thrive in the wetland without any help from us (except for the occasional burn). We do collect seed and plant it in some of our wet mesic prairies (such as the Barn, Crane, and Valley Prairies), but they generally seem to do better on their own than with our help. Right now, the wetland adjacent to the Crane Prairie is lush with these species.

For several years we had cardinal flower in the Crane Prairie but this year it is absent, although the site where the above photo was taken was less than 10 feet from the Crane. Who knows?


Blogger Peter said...

I was looking for cardinal flower at PVC the other day, but unsuccessfully. Guess I need to go back!

August 21, 2012 at 6:51 PM  

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