“Nevertheless, she persisted.” Mitch McConnell of Elizabeth Warren, 2017
Pale Indian Plantain (Arnoglossum atriplicifolium, formerly Cacalia atriplicifolium*) has been variously described as “conspicuous but rare” by Iltis and Cochran, “a problem” by Tom Brock, “aggressive” and “perhaps not suitable for small plantings” by Prairie Moon Nursery. Plants for a Future calls it “somewhat invasive.” We call it PIP. (Flowering head at left)
In his July 21, 2021 blog, Tom described a massive “wall” of PIP plants in the savanna that had “eliminated a prize purple milkweed site”. Three truckloads of plants were removed from the area! He advocated cutting the stems near the ground and treating with Garlon 4. (See photo below). I quote him: “It is a little disconcerting to have to spend all this effort to control a native species that is really desirable and is found in many savanna species lists.” To this day, though our methods are different from Tom’s, we are still trying to control the spread of PIP at Pleasant Valley.
Pale Indian Plantain doesn’t just grow in savannas. This perennial does well in mesic forests, prairies, sand dunes, marshes, and on stream banks. It grows to ten feet high on narrow stalks, and, to my eye, always seems to dominate a landscape, no matter how many individual plants there are. The flowers (July-September) attract wasp, bee and fly pollinators. The nectar is dilute and reachable by “short-tongued” insects. The plants spread not just by seed but also by means of underground runners or rhizomes (Prairie Nursery says that there is a fibrous root component).
Here is a dried and pressed specimen of PIP from the University of Wisconsin Herbarium. Note remnants of rhizomes at upper left.
History of our PIP control methods:
Tom’s method involved cutting and removing the PIP plant material and treating the cut stems with Garlon 4. This was done before full flower and on flowering plants. The work began in 2011. Below is his example showing treated stems.
Our current PIP control protocol begins a few weeks after a spring burn, when the plant leaves are emerging (ideally three to six inches long, but this varies). We apply Escort (1 gram per gallon) using a three-gallon backpack sprayer (methsulfuron methyl 60% – MSM60 – crystals with about 50 ml surfactant and sometimes a pinch of Induce if the ground is moist). Sometimes a given area is re-visited after a couple weeks to get later emerging plants. Care is taken not to spray in wind and to limit the spray cone to the leaves. We compared the relative effectiveness of Garlon 3a, Garlon 4, Roundup and Escort on newly emerged PIP leaves and found, after several years of experiments, that Escort does the best job of eliminating PIP with a minimum of collateral damage.
Lastly, in late summer and early fall, we cut off any fully-flowering or seeding PIP heads and bag them for disposal. Our PIP population is very much reduced now (2023), though we still find unexplained “outbreaks” of several to a dozen (or more?) plants.
If you decide to control PIP, know that the effort will be costly and use management time for many successive years. PIP resists being controlled. We persist. I wonder if the rhizomes may be stimulated by chemical control methods or disturbance in general. At a minimum, if you want to do something, remove the fully flowering heads, or better, the seed heads before they start shedding seed. Premature cutting may also stimulate a rhizomes response, so don’t be too eager to decapitate. We also discourage annual burning of a problem PIP area. Further studies are needed for sure, and might qualify as part of a PhD thesis? Is PIP a pioneer species that will naturally diminish as your prairie matures? Do you really have too many? Can you count them? Are they eliminating rare native species? Do they resist yearly interseeding methods? When you kill off a PIP area, what replaces those plants? Nearby native species? Canada goldenrod, ragweed, woodland sunflower? Another aggressive native, or worse?
At right is an area of Pale Indian Plantain in a prairie at Fair Meadows, the new (third) 2023 Madison Audubon sanctuary, donated and managed by Penny and Gary Shackelford. It will be interesting to check in with them in ten years.
Bottom Line: We have been successful controlling Pale Indian Plantain in our prairies and savannas. As of this writing, our efforts continue. We spray emergent plants in burned areas in the spring with Escort, and we collect seed heads in the Fall.
“I thank whatever gods may be for my unconquerable soul.” Invictus, by William E. Henley
(A single PIP in the Valley Prairie at Pleasant Valley, 2023)
*Footnote: the genus name Cacalia was used previously for a group of plants now belonging to eight different genera. In 1998, the Committee for Spermatophyta decided to reject this name, declaring it “nomen rejiciendum” (rejected name) under the International Code of Nomenclature. All former Cacalia now have other genus names. For example, Cacalia tuberosa is now Arnoglossum plantagineum. And Sweet Indian Plantain is now Arnoglossum suaveolens (sweet-smelling or fragrant).