Native plants and insects have lived together for thousands of years and depend on each other for survival. Over time, they have developed specialized partnerships. For example, some plants have compounds in their leaves that are toxic to many insects as a way to protect themselves. Some insects have developed a resistance to these compounds which allows them to eat those plants, possibly giving them an advantage over other insects. This is how the monarch butterfly came to depend upon milkweed plants.
Great Blue Lobelia in FT Proctor Park
Our locally native plant Lobelia siphilitica, known as great blue lobelia or blue cardinal flower, is a great example of another type of specialized partnership. You may not have ever seen this plant, or even heard of it. It was recommended to us by local native plant enthusiasts, and so last year we planted blue lobelia in the Peace Garden at FT Proctor Park. We quickly fell in love with it – and think you will too!
Blue lobelia grows 2 to 3 feet tall with spikes covered in blue flowers from late summer through fall. It is easy to grow and tolerates moist soil in full sun or part shade making it a good choice for a perennial garden bed, rain garden, or naturalized areas along creeks or woodland edges.
What makes this plant more interesting is the shape of the flowers. The lower three petals of the flower provide a landing pad for a bee of the correct weight to settle on. This will depress the petals, opening a “gate” for the bee to crawl inside the flower and reach the nectar. The bee then dives in head-first with only its bottom sticking out.
Bumble bee on blue lobelia. Photo courtesy of Heather Holm
The bee’s long tongue allows it to lap up the nectar that’s out of reach of other insects. While the bee is in there, pollen is brushed onto the bee’s back. The bee drinks the nectar for energy, and carries the pollen back to the nest. As the bee continues this work, pollen is brushed onto other flowers it encounters, pollinating the plant which begins the fertilization process and enables the plant to proliferate.
Other bees that aren’t the right weight, or don’t have long tongues, can access the nectar by chewing a hole in the base of the flower and taking the nectar that way. Hummingbirds and some butterflies, with their long mouth parts, are able to reach deep into the flower to access the nectar. But this plant is mainly pollinated by our native bumblebees which are never far when blue lobelia is in bloom.
Photo courtesy of Heather Holm
Not only does blue lobelia have flowers that are perfectly structured for our native bees, almost to the exclusion of all other pollinators, but they are also blue, a favorite color of bees. Contrast this with the more popular red cardinal flower, Lobelia cardinalis, which you might know of as a favorite of hummingbirds, which prefer the fiery colors of red and orange. These two varieties of lobelia can be found in nature growing together, thereby providing sustenance for very different pollinators in one location. These types of specialized relationships and co-dependencies exist all around us! By learning more and planting species like blue lobelia, we hope to encourage and foster these relationships at FT Proctor Park.
To learn everything you ever wanted to know about blue lobelia, visit https://growitbuildit.com/blue-lobelia-siphilitica/
To read about the unique pollination of blue and red lobelia, visit the Prairie Ecologist here: https://prairieecologist.com/2013/09/24/hubbard-fellowship-blog-lobelias-and-pollinators/
Thank you to Jill Shultz for contributing to this post.
