Scorpion Tail is a native mystery, easy to find but tough to understand distributed in South Florida, South Texas, the Caribbean, and South America. Gardeners like it for its delicate charm. The ancient Mayans used it in formulations against gastrointestinal infections.
What I find remarkable is its precision. Along that “scorpion tail” inflorescences the flowers are lined up perfectly by age, the youngest at the tip. Toward the base they are post-opening and get older, with only one flower open along the entire wand, the ones further out being all buds, and the ones toward the base all being developing fruits.
The flowers are visited by butterflies but not much. I have it in my butterfly garden at home, and I never detect a visit there, despite scores of butterflies lighting on other flowers all day long. There is “no way” every Scorpion Tail flower receives a butterfly visit. [Note added after this blog incubated. My friend and native plant expert Dane Boggio mentioned seeing a Cassius Blue on one recently, and we looked at several Scorpiontails in Lake Worth 8/7/2021. While we watched, a number of honeybees visited, as did one small Hairstreak (?) butterfly. Dane and a reader comment below caused me to suspect that I may have overstated the rarity of butterfly visitation, all depending on what is meant by “rare.”]
Yet every flower forms a fruit. That suggests self-pollination, and various botanists have surmised selfing in varied species of Heliotropium. But who knows…the floral biology of H. angiospermum has never been studied, so let’s be pioneers and take a stab at it.
The open flower looks normal enough, with a ring of five well separated pollen-making anthers around the opening inviting a butterfly to do what the birds and the bees and the butterflies do.
The next day is more interesting. The flower does not merely close, but the petals clench in tightly like a clenched fist. Cutting open such a clenched flower shows the anthers (white line in photo) now mashed together, the broad but short mushroom-shaped stigma (black line) below them. Perhaps significantly, alongside the stigma is alongside a brush of hairs (red line). Looks to me like pollen might fall into those hair, while the flower is open or later, and then the clenching upon closing might push the hairs up against the stigma like a pollen paintbrush.
Hmmmmmm…it might work that way (or not), and we’ve had a fist peep at a question nobody has explored to date. Call it a working hunch.