Making a flower

an intricate dance of parts

Animal-pollinated plants typically make a flower to attract visiting animals. A straight-forward example is a salmonberry flower, familiar to all of us: there’s a circlet of pink petals surrounding a yellowish center composes of male (stamens) and female (pistils) parts. In other cases, Mother Nature has designed a more complex arrangement of colorful petals, as in lupines or orchids.

Turn the salmonberry flower over and look at its underside, where it attaches to the stem. There is a more-or-less cup-like structure (the calyx), composed of several elements called sepals, which are usually green. The calyx covered the developing flower bud and often remains behind an open flower, providing support.

In some species, however, the sepals have become part of the flower—they are colorful and not hidden behind the petals. The fireweeds are good examples: the four wide, pink petals alternate with narrow, darker pink sepals. Three-leaf goldthread, common in subalpine meadows, has several white sepals surrounding stamens, pistils, and some golden petals, shaped like tiny trumpets, that are serving as nectaries.

Fireweed flowers have narrow, dark pink sepals between the wide, paler-pink petals, possibly making an added attraction. Photo by Kerry Howard

Red columbine is a more complex example. Here, the petals are the five yellow funnel-like structures that have long, reddish nectar spurs projecting from the other end of the flower. The five red, flaring wings are the sepals.

The view of a red columbine flower for an approaching pollinator: five spread-out red sepals and five yellow petals opening into reddish nectaries extended behind the flower. Male and female parts protrude in front of the openings and would be contacted as a pollinator probes for nectar. Photo by Kerry Howard

The wild iris goes still further—the three drooping, purple pieces are the sepals, comprising the main part of the flower. The petals are very small, just visible between the bases of the purple sepals. In domestic, horticultural irises, the petals have become much larger, standing up above the sepals (assuming that the ancestor of domestic irises was similar to our wild iris, horticulturalists presumably have selected for greater petal size over a number of generations).

Some plants have abandoned petals altogether, making a flower of showy sepals: marsh marigold, narcissus anemone, Sitka burnet. So, if you look at the back side of those flowers, you see no sepals.

However, one cannot conclude from an observation of ‘no sepals’ that the sepals are in the flower somewhere. That’s because some species drop their sepals fairly early in floral development; baneberry and some buttercups do so.

Attractive displays sometimes incorporate elements that are not, technically, part of the flower. I’ve previously mentioned dwarf dogwood with its white bracts (modified leaves) around the central flowers. Perhaps the best known plant using bracts to make a conspicuous display are the horticultural poinsettias so commonly sold for winter holidays. The sometimes rather colorful but very small flowers are clustered in the middle of all those gaudy bracts.

Do all those details of botanical anatomy matter? Not to those for whom flowers are just part of the scenery. At a trivial level, attention to such details as a bit like a game, a jigsaw puzzle, accounting for all the pieces and fitting them together. At another level, the various contrivances that make a ‘flower’ suggest questions about the relationships with pollinators (and other possible factors) and thus (eventually) to understanding more about the lives of these plants. Here are a few such questions (and no answers, although they could be addressed by experiments or, in some cases, by close examination of the evolutionary history):

–Are fireweed flowers with colored sepals between the petals more attractive to pollinators than those that lack them?

–Colored bracts or sepals around a flower can make the display larger. How does that affect pollinator behavior?

–Horticultural irises, with their tall petals, are (presumably) more attractive to humans than the wild forms with the tiny petals. Although gardeners may not care, do the pollinating insects such as bees react differently?

–Does converting showy petals to nectaries (albeit colorful ones), as in three-leaf goldthread, allow more nectar to be produced or favor visits by certain kinds of insects?

–In the case of columbines, the elongated petals make a nectar spur that can only be accessed properly by long-billed birds or long-tongued insects, effecting pollination. Many other species in the buttercup family have showy petals bearing small nectaries. The nectary development and specialization in columbines included making the petals less conspicuous, except when the sepals are fully reflexed or when viewed from below the pendant flower. Did that development make it useful for the sepals to be so showy? 

–And why do some plants just drop their sepals, while others have no petals but only sepals in the ‘flower’.

As usual, asking questions leads to still more questions. But if curious naturalists didn’t  keep asking, there are many things we’d never know.


…and some excitement!

After hearing about the flocks of migrating songbirds out on the wetlands, I ambled out there and found longspurs and buntings, but I missed seeing the gray-crowned rosy-finches. So the next day, I went out there to look again. After a long lonely stroll, I finally spotted my birds—a flock of small dark birds accompanied by a couple of buntings swirled overhead and swept down into the grasses. Yes! Although they were barely visible as they scuttled about in the bent-down grasses, they were surely rosy-finches.

I don’t see them very often—they usually nest in rock alpine tundra, scree slopes, and cliffs above timberline. The breeding range extends from Montana northward through much of Alaska to the Aleutians and Bering Sea islands. There are subtle differences in plumage among birds that nest in the Interior, coastal areas, or the islands—differing amounts of gray on the head and darkness of body plumage. The Bering Sea nesters are bigger and darker than the others, with more extensive gray on the head, and they can nest at sea level on those barren islands. Years ago, an invasion of gyrfalcons nearly wiped out the rosy-finch population on the Pribilofs, but the population gradually recovered. The island populations have an earlier starting time and a longer breeding season than the birds in the mainland mountains, and they often nest on buildings there.

Rosy-finches are socially monogamous and (unlike longspurs) the males are very attentive to their mates. Males don’t hold big, multipurpose territories but defend their mates and nests. The female builds the nest, accompanied by her mate as she gathers material, and the male sometimes brings nesting material to her. He guards her well from other males during the egg-laying period when she is fertile. Females incubate clutches of three to five eggs for about two weeks and their mates bring food to them while they do so. Both parents feed the chicks for two or three weeks. The chicks can fly when they leave the nest but are tended for a while by their parents.

Rosy-finches (and other finches too) can carry food in a pair of buccal pouches, located under the tongue and extending back to the upper throat area. Both seeds and insects can be carried this way, to be delivered to mates and chicks. Like many other finches, including crossbills, rosy-finches are attracted to snow or soil on which some animal has urinated; they’ll also sometimes come to wave-washed beach logs. They are after salts and perhaps other minerals that are in short supply in many seeds. These birds aren’t the only ones: butterflies also gather on urinated soil for the same reason; we call that behavior ‘puddling’.

Meanwhile, back at the ranch: I looked out my windows one evening and saw an adult northern goshawk hopping along the bank of the pond, intent upon a female mallard that swam in a narrow channel between melting ice and the bank. All the other ducks were gone, leaving her to her fate. The goshawk jumped that mallard from the bank, then from the ice, then the bank again, or the ice, at least twenty times. Each time, she dove with a great flurry of wings and splashing water, leaving the hawk with wet feet and feathers. Back and forth she swam, quacking, in that narrow channel, always staying in the same ten-foot stretch. When I looked more closely, I could see why—she had (sensibly!) chosen a stretch that was semi-protected by branches that prevented aerial attacks and limited the hawk to pouncing from the sides of the channel. Eventually the hawk left, still hungry, but the duck continued to vocalize for some time as she gradually settled down and then departed. Whew!

On woodpeckers and bears

some early-summer observations and stories

All quiet on the home pond, just a few loafing male mallards and a wandering bunch of big ducklings. Not so, on the suet feeder, occupied by a male hairy woodpecker. An adult nuthatch was taking issue with his occupancy, darting at him repeatedly, making him duck and dodge. Eventually, both birds departed. The nuthatches have been feeding a sturdy juvenile, stuffing it with suet and peanut butter (and insects too, I hope), and perhaps there was a sense of ownership. But it was certainly a surprise to me, seeing that little nuthatch go after the woodpecker that weighs about six times more.

Up on Eaglecrest’s Lower Loop, a three-toed woodpecker was drumming energetically on the top of a tall dead snag. Presently, another woodpecker flew in and they both went off somewhere briefly, and then one came back to the snag. I don’t know what was going on, but that prompted me to learn a little more about their drumming behavior.

Both male and female three-toed woodpeckers drum (as is true of at least some other species too). There are two styles of drumming: fast, which is more common, and slow. Fast drumming typically includes about sixteen hits at an average rate of over thirteen hits per second. It is used primarily for territorial advertisement, often in response to another drummer. Slow drumming  averages about nine hits at a rate of just over eleven hits per second. It occurs between members of a pair, apparently as a way of locating each other and getting together.

There hasn’t been much bear traffic in my yard, but up near the visitor center, a friend made some good observations. Two little bear cubs were up in a cottonwood tree, pulling in branches and snacking on the ripening seed pods, while mama rested at the foot of the tree. One of the cubs started to descend but panicked and started bawling. So mama scrambled up to guide the little fellow down, the sibling cub coming along too.

A number of years ago, we often saw bears up in the cottonwoods, feeding on male and female flowering catkins and on seed pods, but that activity seemed to have diminished recently, so it was good to hear that our bears still do this. When we first noticed this behavior, years ago, it seemed perhaps a bit unusual and certainly interesting, so we wrote a small paper about it and sent it to a journal. “We” in this case was comprised of me, three very experienced Forest Service rangers, and an ADFG statistician. Well!! The journal rejected our paper, disbelieving our observations—even though black bears all across North America are known to eat catkins of many species! Now, I’ve written a lot of scientific and natural history papers, and as an author, I know to expect journal editors to request revisions, sometimes extensive ones. But this was the only time in a long career that I’ve experienced rejection based on disbelief. Harumph (and a few other, unprintable, words)!  Fortunately, we had more photos of our bears in action in our cottonwoods, and those photos eventually persuaded the journal to accept our paper.

Some of the trees near the visitor center still show signs of bears getting access to catkins and pods: some large branches are missing altogether, broken off when bears pulled them in toward the trunk where they perched securely. Many small branches are gone, too, broken off by bears or by porcupines, which relish the catkins and pods too. We noted that female trees endured heavier damage than male trees, probably because of the extended depredation of seed pods after the floral catkins were gone.

Squirrels and mice relish the seeds in the seed pods too. I find evidence of their work on the ground and occasionally see them in action.

Summer comes

in praise of the season

It’s official now. Never mind what the calendar says; the fireweed flower buds are emerging from tall, leafy stems, and that’s the seasonal clock that matters!

A trip up the tram in mid-June encountered lots of snow across the trail, becoming too much for me just a little way above the cross. Even so, on the lower part of the trail, narcissus anemones, yellow violets, and Cooley’s buttercups were showing off, along with an alp lily, a few pixie eyes, one deep purple Alaska violet, and a few others scattered about. Fox sparrows, juncos, robins, and Wilson’s warblers sang.

Just ten days later, the trail was almost clear of snow as far up as I could see, although I found one old ptarmigan burrow with the usual fecal deposits, beside the trail. Going just a few levels beyond the hang-gliders’ wind-sock, I noted about thirty kinds of flowers. Now the Alaska violets were in full swing; buttercups and anemones still flourished and were joined by northern geranium, spotted saxifrage, roseroot, moss campion, fine displays of villous (woolly) cinquefoil, and many others. A friend reported that the glaucous gentians were blooming nicely, higher on the ridge. What a difference those ten days made!

Alaska violet. Photo by Deana Barajas

At the very end of June, on a low tide, a friend and I wandered out to some of the dredge islands in the wetlands off the dike trail. Sculpins scuttled away in the nearly-dry channels. A few hot, sunny days had made the lichen carpets on the islands dry and crispy, but they still offered a tapestry of varied color and texture. Savanna sparrows sang from the grassy areas and shrubs along the edges, song sparrows from the thickets, hermit thrushes from the spruces. Beach rye was shedding pollen, cow parsnip’s big, white inflorescences were platforms for nectar-sipping flies, and an angelica inflorescence was totally covered by tiny flies doing the same. Willow seeds freed from their capsules were floating about, sometimes getting caught on branches, making fluffy clumps. Mayflower and dwarf dogwood plants had established in some places, but they were small, pale, and without flowers, quite unlike the ones growing in forest. The little plant called sheep sorrel (an introduced species gone feral) had opened some of its tiny reddish buds, and yellow rattle (or rattlebox) was flowering too.

There was, of course, the usual accumulation of trash—spent shotgun shells, plastic jugs, beer cans, and what not. We had a big yellow litter bag, so there is less of that now. As we picked up half of a damaged plastic jug, we panicked a colony of ants that had built their tunnels under that convenient roof; we did what we could to give them a new roof of natural materials. Ants arrive out there when a winged queen with fertilized eggs wafts over the channels and sets up shop wherever she can find a place. Ants seem to be so uncommon here, that I get a bit excited when I find some.

A few days later, three friends wandered out the Fish Creek trail and perched for lunch on a beached log. We were amused by a pan-handling squirrel that came up behind us, clearly expecting some snacks. It got some, of course. Out on the exposed tide flats, an eagle stood quietly, no food in-hand, doing nothing in particular, but a mischievous crow dove at it repeatedly, even striking it occasionally, for no apparent reason except devilment.

We walked around to the end of the ‘island’ and looked out over the tide flats. Suddenly, a gang of fifty or more crows rose up and flew toward the trees behind us, making a tremendous racket, sounding very angry. The crows converged on one spot at the edge of the trees, clearly focused on something down under elderberry bushes and sweeping spruce branches, hollering and swooping down at whatever it was. Fifty crows can make a terrific amount of noise!

So, of course, we had to watch. The sharpest observer among us finally spotted a bird (or, rather, part of one), barely visible under all the brush. At first, all I could see was a small patch of gray feathers, surrounded by green elderberry leaves. But on the other side of those green leaves, close to the ground, I finally could make out a bird head—a glaring eye and a red-stained beak. That bird didn’t move while the crows were furiously mobbing it—yelling bloody murder and crashing into the vegetation around it. After many minutes, though, the hidden bird moved a few feet and stood up; now we could see the front of it—a belly marked with some dark, horizontal bars.

Putting the visible pieces of the harassed bird together, we determined that it was a peregrine falcon, a deadly predator of other birds, although we couldn’t see if this one held any prey in its feet. But mysteries remained: How did the gang of crows out on the tide flats know it was there? Did they see it come in or did a lookout in the trees notify them? Had the falcon captured a small bird or even a young crow, which would set off all the crows’ alarm systems?

Eventually, the hubbub subsided, although the crows still kept watch from perches in the trees. The falcon remained almost invisible in the thick foliage. We didn’t stay to see what might happen when the falcon tried to leave its leafy cover.

Flower colors

musings on the palette of summer

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!