Self-Heal, Prunella Vulgaris

Day 354: Self-Heal's unfortunate similarity to the invasive Ajuga reptans invariably causes me to accuse it falsely of being an interloper until I bend over for a closer look. When not in flower, it is much harder to distinguish Prunella (the native pictured above) from Ajuga. The secret is in the leaf shape, and it's not always easy to make a judgment call. Those of Prunella are typically shorter and rounder, but young Ajuga leaves may appear identical, so when possible, you should examine a leaf emerging from halfway up the stalk. These leaves are likely to be more fully developed, and the width/length ratio can be more easily ascertained. When plants are very young, i.e., at the point of growth when the first true leaves appear, a trained eye may notice a reddish tint to the stems of Ajuga which is not present in young Prunellas. I suspect that in my "de-ajuga-fication" of a certain patch of Longmire meadow, a few innocent Prunellas may have been rooted out as well, but Arnie and I agree: better to err on the side of caution. One little Ajuga in the Prunella patch can create problems for years to come.

Good And Evil

Day 270: In close-up, it's easy to see that these two plants are not the same species, but from a distance of six feet, you might simply think one was a colour variation of the other or a fading specimen. The similarity of the two allowed an invader to go unnoticed for a number of years until it had spread over an area encompassing approximately 600 square feet of Longmire Meadow. It was only through the curiosity of a Park colleague that its true nature came to light. Once we determined that it was not our native Self-heal (Prunella vulgaris ssp. lanceolata, left) and was in fact Carpet Bugle (Ajuga reptans, right), we began working on a plan to eradicate it.

Over the next ten days or so, I pulled together a team of volunteers who assaulted it in a manner not unlike the grid-by-grid excavation system used in archaeological digs, and on Wednesday when they left the site, about 75% of the weed was gone. Yesterday, Plant Ecologist Arnie Peterson took a break from his office duties to help me clear the remainder. A total of 50 man-hours went into the project, contributed by eleven "deveg" team members. Nine full-sized trash-can liner bags filled with Ajuga were taken away from the site.

Ajuga propagates both by seed and by stolon. The site will have to be monitored closely for the next several years to be sure that this invasive species doesn't regenerate and get a toe-hold again.