Over the last few years, this weekly series has inspired me to visit many natural areas for the first time on the hunt for new (to me) Iowa wildflowers, such as wild blue sage, dwarf larkspur, and wood betony. Today’s featured plant was hiding in plain sight, barely a quarter-mile from my home. I’d noticed it before this summer, but for some reason assumed it wasn’t native and never learned its name until a couple of months ago.
Tall blue lettuce (Lactuca biennis) is native to most of Canada and the United States. Sometimes called blue wood lettuce, biennial blue lettuce or woodland lettuce, the plant thrives in shady, wet habitats, including woods, swamps, and stream banks. I took all of the enclosed pictures on the Windsor Heights and Urbandale bike trails, which run along North Walnut Creek.
For botanically accurate descriptions of tall blue lettuce foliage, flowers, and seeds, I recommend the websites Minnesota Wildflowers, iNaturalist.org, or Friends of the Eloise Butler Wildflower Garden. According to the Lady Bird Johnson Wildflower Center at the University of Texas, the roots and sap of tall blue lettuce have had some traditional medicinal uses, but “people with sensitive skin […] may develop rashes from contact with lettuce sap.”
Leaves higher up have a different shape:
In mid-August, some tall blue lettuce plants were just starting to flower, with most buds still closed.
Other plants had more flowers open around the same time:
Flowers are most often pale purple.
They can be almost white.
These flowers were a deeper color than most in my area:
This was one of the shortest tall blue lettuce plants I found blooming. The small, darker blue flowers closer to the ground are dayflowers.
Tall blue lettuce in the foreground; the plant with white flowerheads is some kind of boneset, possibly tall boneset. The yellow flowers in the background are brown-eyed Susan.
Tall blue lettuce gone to seed in early October: