(The origin of “Liatris” is not known, perhaps a very old name. Alvin Chapman was a physician and seminal Florida botanist.)
Something’s odd in the Delaware Scrub Natural Area in Jupiter. Driving by yesterday, what is that tall purple wildflower in the scrubby sand? Stop, go back and check it out—well, how weird, it is Chapman’s Blazing Star. Liatris chapmanii, which always blooms late summer and autumn, is in full bloom across one corner of the natural area. How can that be? It is one of the earlier-flowering Liatris species, August-October, but May is absurd.
The main reason many autumn flowers bloom in the harvest months is a response to the lengthening nights after the June 21 summer solstice, the daylength cue sometimes interacting with temperature. If the long night is interrupted with artificial light it can throw off the plant’s internal clock. When horticulturists deliberately break up long nights with artificial light to manipulate flowering, turning on the lights is called a “NI” (night interruption). Researchers Ignacio Espinosa and Will Healy in Maryland, interested in commercial year-round Liatris (L. spicata) production as a cut flower, applied different combinations of temperatures and NI’s to influence the Liatris flowering season in varied ways. Our L. chapmanii is more “tropical” so its temperature-related behavior would differ from more-northern L. spicata.
All that being so, what triggered flowering in Chapman’s Blazing Star 6 months out of sync? Looking around the site of the funny flowering, there is “NI” on a pole…a street light (actually two of them) beaming directly onto the Liatris patch. Wonder if anything else there flowers at the wrong time.