Monitoring an Invasive at Tire Mountain

The stretch of deltoid balsamroot (Balsamorhiza deltoidea) along the trail is always a favorite spot for photographs.

Emily looking at an almost solid spread of knawel that was yellowing as it died back.

Many years ago, I noticed a weed in the large meadow at Tire Mountain I call the dike meadow because of the prominent dike at the east end. It is called Scleranthus annuus and goes by the unusual name of annual knawel. Like some other members of Caryophyllaceae, the pink family or carnation family, it has inconspicuous, petalless flowers. It would be easy to miss if it didn’t spread so badly. I’d more or less forgotten about it and hadn’t realized how large the population had become, in spite of passing it numerous times over the years. Luckily, Bruce Newhouse had noticed and called attention to it to the botanists at the Middle Fork District of the Willamette National Forest. On June 20th, I accompanied Leela Hickman, the assistant botanist, along with seasonals Sol and Emily and a crew of four interns from the Student Conservation Association to take a look at the knawel. Of course, we looked at all the native wildflowers as well. Leela was the only one of them who’d been to Tire Mountain, and that was on the trip I led for the Native Plant Society of Oregon last year (see NPSO Annual Meeting Trip to Tire Mountain). So other than seeing how bad the knawel had spread, everyone enjoyed the beautiful display of wildflowers and the many interesting insects at one of the best wildflower trails in the district.

Up close, knawel isn’t the least bit showy. Its tiny flowers are petalless bells.

Sol spotted this checkerspot chrysalis hanging from a parsley fern (Cryptogramma crispa). Earlier we had seen a caterpillar as well as adult checkerspot butterflies. We also watched a beautiful cobalt blue jewel wasp crawling around on the rocks, but move too fast for me to get a decent photograph.

We spent a while lunching at my favorite spot on the north side of the ridge. It’s cooler there, and there are some species you won’t see on the south-facing side. We saw a beautiful cobalt blue jewel wasp crawling around on the rocks, but it moved too fast for me to get a decent photograph. Sol also found a checkerspot chrysalis right where we were eating. I don’t get to see those very often. One of the things of interest we noticed were that both types (sometimes considered varieties) of littleleaf montia (Montia parvifolia) were growing in the area. I’m not sure if I’ve ever seen them side by side before. The common one has small white to pinkish flowers. It’s cute but hardly showy. The other one is larger in all its parts and has bright pink flowers. I used to have it in my garden, but now only the small-flowered one is appearing in all my pots. It makes little offsets in the leaf axils, so it spreads very easily—a good adaptation to growing on rocky slopes and cliffs.

Littleleaf montia. On the left is the common small-flowered form. On the right is the showier type sometimes considered variety flagellaris. Broadleaf stonecrop (Sedum spathulfolium) and spotted saxifrage (Saxifraga vespertina [formerly bronchialis]) grow in the same rocky area.

Emily checking the plant list I gave her while admiring the colorful show of harsh paintbrush (Castilleja hispida), large-flowered Blue-eyed Mary (Collinsia grandiflora), rosy plectritis, and chocolate tips (Lomatium dissectum).

We saw lots of little acmon blues flitting around the meadow. This one is nectaring on northern buckwheat (Eriogonum compositum), also one of its host food plants. You can see the silhouettes of some dark aphids, abundant on some of the plants.

From the north side of the ridge, we also got a good look at what I call “Mistmaiden Meadow” that I’ve been exploring the last year. I had been hoping to show the Forest Service botanists this special site last year, but with their busy schedules and the Bedrock Fire in the area later in July, it had never worked out. But since they were already planning this trip to Tire Mountain, and Mistmaiden Meadow is only a few miles away (2 air miles, 4 or so by road), we headed over there after we returned from Tire Mountain. We were only able to spend an hour there, but it was enough to give them an idea of how diverse and lush the plants are there and also how to access the hidden meadow. It was as glorious as it was last year. The display of rosy plectritis (Plectritis congesta) was stunning, and there were still enough Thompson’s mistmaiden (Romanzoffia thompsonii) in bloom that I was able to show them what this endemic looks like and how to differentiate it from the similar Nuttall’s saxifrage (Cascadia nuttallii) that was taking over from the mistmaiden in the seepy areas. Sol wondered whether this is what heaven looks like. Being among all those wildflowers is heaven on earth for me at least!

From the north side of the ridge in the largest meadow at Tire Mountain, we had a good look (this is taken with my zoom lens) at our next destination: Mistmaiden Meadow. You could see the pink patches of rosy plectritis even from a couple of miles away.

Up close, the rosy plectritis at Mistmaiden Meadow was outstanding. The great camas (Camassia leichtlinii) was also at peak but closed for the afternoon.

One Response to “Monitoring an Invasive at Tire Mountain”

  • I should have mentioned that there are plans to deal with the knawel. Options discussed include hand weeding, smothering with a covering, and spraying. Probably a combination of techniques will be needed. As an annual, it will have created a seed bank that will require more than one year to deal with. Since some of it was already dying back, it is probably too late to do anything this year. Hand pulling all those plants will be quite labor intensive, but smothering can only be done in areas where the natives have already been wiped out. There’s hesitation about using herbicides in an area with so many natives and where there is so much human use, but it may be used in a limited manner. I expect they will also collect native seed from the meadow to reseed after the knawel is removed. It will be interesting to see how the Forest Service ends up battling this awful weed. With the amount of visitation of both hikers and bikers, it is surprising there aren’t more weeds along the trail.

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