Plant Profile: Lobelia spicata

A nice colony of Pale-spike Lobelia [Lobelia spicata] is in early bloom in my garden as I sit here one of the last days in June. It is a rather dainty species as compared to its well-known relatives, the robust Great Blue Lobelia and the Cardinal Flower and therefore perhaps less well known. The flower color is a light blue, with a white center and at times a bit obscured by the basal bracts that subtend each flower of the rather slender spike. Flower color can vary quite a bit, from near white to medium blue. The whole plant is less than 2’ tall and easily disappears among taller vegetation at this time of the year. This plant was collected many years ago in Macoupin County where it grows on a number of sites, all of them thinly vegetated gravelly prairie slopes.

In my garden is another Lobelia accession, this one from the poorly drained and seasonally very wet Route 66 Prairie. I established both colonies some years ago to compare some puzzling differences between these populations. Often the ‘best plans of mice and men go awry’. Voles had become a serious problem, eliminating some early species grown for seed production and just ploughing up the soil. Fortunately, a few Lobelias recruited nearby from the seed bank and comparisons could eventually proceed. These plants are even smaller, perhaps 2/3d the size by comparison. The flowering stems have far fewer and smaller leaves and bracts are noticeable only on close examination. The flower color is a very light blue, almost milky – difficult to describe. In a good year this Lobelia, following just the right kind of burns it creates sheets of blue. That always reminded me of an experience, many, many decades ago. I was visiting prairies of southwestern Missouri for the first time. As I was cruising down some country lane on that early spring morning my attention was drawn to a large sheet
of shimmering pale blue out in that low prairie. Then, for a moment it almost seemed like a mirage, a mystical experience. Once close, I stopped of course. It was our Lobelia, blooming along with some early Golden Alexander. That early blooming period nearly matches that of our Route 66 Prairie population. My garden plants have been out of flower for over a month. Their seed has already completely dispersed.

A perusal of the literature, the ‘Flora of Illinois’, but also floras of many neighboring states and more indicates that this species occurs over much of the eastern and central US and has numerous described forms. It is said to be common, even in Illinois. I have seen it only a few times and so have my local botanizing pals. No doubt that is due to a lack of remaining suitable habitat. Let’s face it, our so called ‘Prairie State’ is really just the ‘State of Corn and Beans’. It would be nice to have readers weigh in about distribution and phenology of any central Illinois populations.

The Macoupin County material pretty much keyed out to the variety ‘leptostachys’ and our local variety could be variety ‘spicata’ or ‘campanulata’. I would love to have a taxonomist resolve this. What remains a real enigma though is the phenology. On this the literature is all over the place. Our 2 ecotypes have a gap in flowering of 3-5 weeks according to my observations so far. That much difference would prevent any gene flow, even if the landscape where less fragmented. Is speciation taken place before our eyes? Can we know now or will we have to wait a few more millennia?  The natural world is full of mysteries, even at the local level.