Flower colors

Just before the summer solstice, a little group of friends walked out onto Cowee Meadow. Although it was raining in town, out there, the sun was shining. The meadows were a blaze of color: pink shooting stars, yellow buttercups, and blue lupines covered acres with floral glory. While those species were dominant in the meadows, we counted over sixty species of flowers on our walk (not counting grasses and sedges). We did include the irises, which were just starting to bloom; in another week or two, irises will be the main show.

Among all the blue lupines were three or four individuals with pink flowers, and we’ve sometimes seen very pale shooting stars. On the upper beach, there’s the usual blue-flowered oysterplant, with a few white-flowered individuals—and even one plant that apparently made both blue and white flowers. Rare white-flowered geraniums and beach peas are also reported among the usual purplish ones, and some chocolate lilies have yellow (instead of brown) flowers. That made us wonder about the fate of these mutants—do they get visited by insects or are they reproductive failures?

While cogitating about flower color, we also commented that white flowers seem to characterize more of our native, local flowering species than any other color, although many of those white flowers are small and inconspicuous. There’s a fair number of species with blue/purple, yellow, or pink flowers, but red, orange, and green flowers are rare. However, white may not predominate in our alpine zones–It might be interesting to compare the frequency distribution of floral colors in different habitats and contemplate possible relationships with the available pollinator fauna (or other factors).

A common white flower on the Cowee Meadow trail is dwarf dogwood (bunchberry). It’s so common and familiar that it often escapes notice! That ‘flower’ is really an inflorescence composed of four whitish bracts surrounding a tight central cluster of actual flowers. There were many other things to look at on that hike, so I didn’t take time to inspect those dogwood inflorescences closely.

Photo by Kerry Howard

However, a few days earlier, I had done so on the Eaglecrest Lower Loop—higher in elevation, so the dogwoods were then less advanced and I could observe the seasonal progression of floral development. Some dogwood inflorescences were just opening and the bracts were small and green; the floral buds in the center were dark and tightly closed over the male and female parts inside. On more advanced inflorescences, the bracts were bigger and greenish-white, while the floral buds were still dark and closed. Then the bracts get bigger and whiter, and by the time they are fully mature, the floral buds are starting to open, exposing the sex organs to visiting insects. The flowers ultimately can open by themselves, but studies have shown than an insect visit can trigger floral opening and an explosive release of pollen. In either case, stamens catapult pollen vertically for several centimeters at very high speed, onto an insect or into the breezes. The pollen grains are not sticky, so high-speed release is thought to be necessary for adhering the pollen to an insect. Whether by wind or by insect transport, pollination is only successful when pollen arrives from a different dogwood individual, because this species is self-incompatible. After pollen is ejected, the pollen-capturing surface of the stigma increases, ready to receive incoming pollen. However, fruit-set generally seems to be low.

Another white-flowered plant was blooming profusely in the meadow along the Lower Loop trail: three-leaf goldthread.  This flower looks nothing like the flower of the related fern-leaf goldthread that mostly grows in the forest. The flower is comprised of several white sepals surrounding the sex organs and five (sometimes six) tiny golden trumpets that are modified petals offering nectar to visiting insects. Although I saw no insects visiting a group of open flowers, I watched a small fly working assiduously for several minutes, trying to gain entry into an almost-open bud.

There must be good stories behind the evolution of flower colors and shapes; I wish I knew them!

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July explorations

Toward the end of July I hiked with some friends around Cropley Lake at Eaglecrest. It was the first full day of sunshine after something like three weeks of nearly continuous rain and cool temperatures. We reveled in the dazzling light and warmth. Some of us hoped we’d find yellow fireweed and sky-blue gentians blooming on the soggy back side of the lake, but apparently we were too early. Maybe the unseasonable weather slowed them down.

Swamp gentian. Photo by Bob Armstrong

But there were other things to be seen. Millions of swamp gentians starred the meadows, interspersed with the tiny pink dots of bog cranberry. As we approached the elevation of the lake, there were clear signs of late spring: the last of the spring violets and Jeffrey’s shooting star, and swathes of bog laurel. Late spring mingled with summer: little iris-like Tofieldia and leatherleaf saxifrage, with inflorescences of varied shades of red, were common; grass of Parnassus was about to bloom. Pink paintbrush prefers this habitat to the lower-elevation gravelly flats occupied by the yellow paintbrush species. The big treat was seeing dozens upon dozens of butterworts in bloom. Sometimes called ‘bog violets’ for a supposed resemblance to true violets, butterworts are not related to violets at all (although they both may have purple flowers). Butterworts are insectivorous, catching bugs on their flattened, sticky, yellowish leaves that are not a bit like violet leaves.

Paintbrush. Photo by Bob Armstrong

Earlier in the month, during all that rain, we made a special trip to Cowee Meadow. On a previous visit, we’d finally discovered what the female inflorescences of sweetgale looked like when they were in flower, and now the goal was seeing the mature form. By luck, our timing was good—the female inflorescences made slim, brown, cone-like structures, whose scales opened up to release seeds. By traipsing around for a while in the meadows, we also found more female plants than we’d found earlier, so females aren’t quite as rare as we thought (although still vastly outnumbered by male plants).

We happened to look at some fireweed flowers. I don’t know what attracted our attention, but when we looked attentively, we noticed that many of the flowers had no visible female parts. Fireweed flowers are both male and female, with a set of stamens with pollen-bearing anthers around a conspicuous, white, four-branched stigma for receipt of pollen. But some of these flowers seemed to be missing the big stigma.

After much closer attention, we found that the female structure was there, but small and drooping and apparently with the four branches both short and closed up tightly, as if they’d never fully matured. Fireweed inflorescences bloom from the bottom up, so older flowers are borne below younger ones, with unopened buds up at the top. But age of flower did not account for the development of female parts; both young and old flowers often lacked fully developed stigmas.

What is going on here? Is this just something I should have noticed long ago? Or could the long spell of un-summery weather have made the plants decide not to even try to receive pollen and make seeds?

Everywhere we wandered in the meadows, we found recent bear digs, usually for angelica roots. In some cases, the edible root-nodules of chocolate lily (rice-root) had been incidentally dug up too, but were left uneaten.

Back in the middle of July, on the Crow Point/Boy Scout trail, I watched a hummingbird visiting yellow paintbrush. It dipped in, then floated (or so it seemed) high into the air before coming back down to try another flower in the same patch. It tried a few flowers but soon zipped away, as if to seek better foraging elsewhere.

Red fruits of baneberry decorated the sides of the berm edging the goose flats. The felwort that we often see later in summer wasn’t blooming yet. But the wide meadow between the trail and the river was covered with white arctic daisies (Chrysanthemum arcticum), not to be confused with the weedy, alien white daisies on the roadsides.

A search for Salicornia in the big goose flat was futile for what seemed like a long time. But finally we struck the right microhabitat and found a lot of it—a tasty snack! This highly salt-tolerant annual plant is known as glasswort or saltwort or sea asparagus, among other common names.