Cheering notes

floral memories brighten a gloomy winter

As I sat here on yet another gray and drippy day in mid-January, grousing futilely and needing a cheering thought, there popped up a memory from my old life in the Midwest (probably prompted by recent reading). There are many things in the Midwest that I miss, and one of them is the deciduous forest with its many kinds of flowers in the understory; there are well over a dozen species. It’s a spectacular show in early spring (when my grad students and I did research on seven of them), and other species come along later on.

Many of these early species take advantage of the open canopy that lets in plenty of light before the trees leaf out. The light is used to make carbohydrates for energy (needed for growth and seed development) and a bit of warmth facilitates the activity of insect pollinators. Even the species that don’t flower until later in the season can build up stores of energy to be used at their proper time. I think that the availability of light is probably one of several factors contributing to the floral diversity in the deciduous forest.

All that made me think about our coastal rainforest, whose floor is mostly shades of green, lovely in its own way but scarcely as showy. Here in the coastal coniferous forest, the understory is always dark; the canopy blocks lots of light all year long. And only a few flowers thrive throughout the forest; several others are happier in somewhat brighter places on the forest edges or in canopy openings, although they are sometimes found scattered within the forest.

Whatever the reasons for the dearth of understory flowers here, I chose to contemplate the flowers that regularly decorate the forest floor. They are little points of delight, good to envision on dark day even though their blooming time is still months away.

Bunchberry flowers. Photo by Bob Armstrong

–bunchberry or dwarf dogwood: very widespread in the forest, the four white bracts around a central cluster of small flowers make a good showing. The flowers release pollen in an unusual way: by a special catapult mechanism that throws the pollen up several centimeters. The flowers open elastically, explosively, and extremely rapidly (in less than a millisecond), flipping the pollen-bearing anthers upwards. Flowers may open spontaneously, tossing pollen up into the breezes, or when triggered by the visit of a large insect such as a bee, tossing pollen onto the insect’s body to be carried to another flower. Later on, the clump of red berries is equally showy. The leaves are typically evergreen, but sometimes turn red.

Rattlesnake plantain flowers. Photo by Bob Armstrong

–rattlesnake plantain: an orchid that has nothing to do with snakes or plantains, whose evergreen leaves are sometimes mottled with dark blotches. It produces a spike of white flowers that may be bumblebee-pollinated but are reported to be more often visited by moths in our area. Like all orchids, it depends on mycorrhizal connections with other plants for seed germination and early seedling growth; this mutualism may also supplement the nutrition of adult plants. This orchid can spread vegetatively by rhizomes (underground stems), and we often see patches of it with many nonflowering stems.

Fern-leaf goldthread, male flowers. Photo by Bob Armstrong

–fern-leaf goldthread: the flowers are small and delicate, often male, but sometimes hermaphroditic (both male and female). An individual plant can be change sex expression from year to year; if it produces energy-expensive seeds in one year, it is likely to be male or non-flowering the next year. Later in the season, fruiting plants make an interesting whorl of seed capsules that fling out the seeds when jostled. The leaves are evergreen. Although it is found in dense forest, survival of young plants is better where the shade is less dense. The flowers are pollinated by small flies, such as dance flies.

Single delight. Photo by Bob Armstrong

–single delight or shy maiden: An evergreen member of the wintergreen family, its white flower faces downward until it is pollinated, when the flower raises its face upward, exposing the seed capsule with the tiny seeds to the breezes. The flower is buzz-pollinated by pollen-collecting bumblebees, which vibrate the anthers to release pollen onto the foraging bees.

Western coralroot. Photo by Bob Armstrong

–western coralroot: Spikes of pinkish flowers on pink stems usually appear in groups. There is no green pigment at all and no capacity for photosynthesis; these plants are indirectly parasitic on trees and shrubs, via mycorrhizal fungal connections, and also may be saprophytic (feeding on decayed organic matter). The flowers are visited by bees.

Those species all grow under dense coniferous canopy and are seldom seen outside the dark forest. It seems likely that they are able to inhabit the deep shade because they are evergreen and therefore capable of photosynthesis at any time of year if it’s warm enough, or dependent on other sources of energy. All can spread vegetatively to some degree, by means of rhizomes, and probably all of them form mycorrhizal associations with other plants. At least some of them, including rattlesnake plantain, seem to flower infrequently, suggesting that energy resources may be limited. Self-pollination may occur in some of them, with or without an insect visitation.

One other species is often considered to thrive in dense, moist forest in western North America: three-leaf foamflower. Unlike the previous species, foamflower is not evergreen; it reportedly does somewhat better under less dense canopies and is also seen along trails in more open areas. It would interesting to know how it manages in the deep forest. Other species are sometimes found in the forest, but usually in more open parts of the woods or on the edges: examples include starflower, calypso orchids, three-leaf goldthread, twinflower, two species of twisted-stalk, and violets.

Whether bona-fide deep-forest denizens or dwellers on the fringes, they all provide visual delights, sometimes olfactory treats (twinflower, maybe rattlesnake plantain), and interesting natural history.


Spring has sprung

spring’s many offerings to the senses

Mid-May, and spring things are burgeoning. Deciduous trees leafed out, producing a palette of lively green hues against the somber greens of conifers. Bears and porcupines eat cottonwood flowers, and a mama bear parks her three tiny cubs up in a cottonwood while she forages not far away. Most of the mountain goats around the glacier have moved uphill, but one lingers above Nugget Falls. And a new kid was recently born near there.

Fern-leaf goldthread shows its delicate spidery flowers in forest understory. This plant can change the gender of its flowers from year to year: if it is hermaphroditic (both male and female) in one year and produces fruits, then the next year it is likely to be male only or not flower at all.

Fern-leaf goldthread blossoms. Photo by Mary Willson

A trip into Sheep Creek valley gave us early blue violets, yellow stream violets, and miner’s lettuce. In the valley and on rocky coastal headlands, the villous (woolly) potentilla opened its yellow flowers. The buds of this species are sometimes red, and we wondered why! Near the glacier, the lovely little flower with the silly common name of Sitka mist-maiden and the resounding scientific name of Romanzoffia sitkensis adorns some of the cliffs.

The sweet aroma of skunk cabbage fills the air near large stands of this plant (nothing skunky about it!). Little brown beetles throng to the inflorescences when the flowers are in male phase (with pollen) and can be seen crawling around with their bodies dusted with yellow pollen. In bad weather or maybe just when the temperatures are a bit low, gangs of beetles huddle down in the folds of the yellow ‘hood’ of the flower. The beetles seem to mate on the inflorescence and can often be seen there in pairs. Some will eventually fly to find a skunk cabbage that’s in female phase, carrying pollen and fertilizing the future seeds.

On one of the local trails, we thoroughly enjoyed a close-range look at a male ‘hooter’ or sooty grouse performing his full-blown advertisement for females. Throat pouches puffed out with each hoot, tail fanned like a strutting tom-turkey, feathers fluffed—he was an impressive sight. And he could not have cared less that we were closely observing it all.

I’ve recently seen robins carrying grassy nest lining, hermit thrushes carrying beakfuls of moss, and hawks migrating above Gold Ridge. Fox sparrows are singing. Mallards and juncos are already on eggs. Chickadees now have nestlings to feed. But late arrivals, such as Swainson’s thrushes, are not here yet.

Remember that long stretch of hot sunshine we had earlier this month? Everything was dry and dusty. Then came a small rain shower, just enough to dampen the leaves and rocks—and elicit that special, refreshing aroma that only occurs after a rain that follows a dry spell. From a hiking companion I learned that there is actually a word for this! It’s called ‘petrichor’, a word invented in the 1960s by some Australian scientists who were studying these smells. The ‘petr’ part refers to rock and the ‘ichor’ part comes from Greek mythology: the Greek gods were said to have a golden fluid (ichor) in their veins instead of blood; it was supposedly toxic to mere mortals (I wonder how that was discovered!). The scientists discovered the principal sources of the lovely aroma. Some comes from metabolic by-products of certain soil bacteria, and some comes from volatile plant oils that are produced in the dry time and absorbed by clay and rocks. Rain releases all these chemicals into the air.

I hang around rather often up near the glacier, watching porcupines, or ducks, or whatever is there to be noticed. One day a friend said: your nose is all yellow! Well, I’d been sniffing male willow catkins, to enjoy their faint, sweet smell, and got pollen all over my nose (no, I did not then visit female catkins and try to deposit pollen…).

The progress of spring offers much for all the senses. Try it!

Being a flower

it isn’t easy!

The first day the tram was running, a friend and I went up to try the trail on Gold Ridge. We didn’t get very far, being unwilling to cope with lots of trail-covering snow, and settled instead into a sheltered spot, out of the wind and in the sunshine, for a little picnic.

The false hellebore (= corn lily) was just poking up above the ground in snow-free areas, and fox sparrows and robins were singing. Especially enjoyable was the cheerful sight of yellow-flowered Cooley’s buttercup (now known as Cooley’s false buttercup), which some fastidious taxonomist has decided is no longer a ‘true’ buttercup (genus Ranunculus) but rather a poor cousin–a ‘false buttercup’—in a different genus.

Cooley’s false buttercup. Photo by Kerry Howard

I doubt that the wide-open flower of this (former) buttercup has a special kind of pollinator. It is probably visited by several types of insect, from bumblebees to flies and beetles, some or all of which could be effective pollinators.

Looking at those flowers, however, gave rise to a train of thought in my messy brain, starting with the question of what a flower does and the varied problems a flower has to solve.

The most fundamental function of a flower is sexual advertisement, sometimes flagrant, sometimes coy. The advertisement is commonly visual—colored petals (visible and sometimes UV wavelengths) or petal-look-alikes, pollen-bearing stamens (the male parts, often displayed conspicuously), multiple flowers bunched together to enlarge the floral display. Less accessible to humans but often an essential component of advertisement is aroma, appealing to the scent organs of various animals—in our region, chiefly insects. Nectar, and pollen itself, serve as pollinator rewards for visiting a flower.

Traditional botanists measured the reproductive success of plants by seed-set—the female function of flowers. That view of course neglects the (in most cases) necessary role of males in pollination and seed production, and the fundamental biological fact that plants can pass on their genes through both male and female functions. Passing on genes is all that counts in the evolutionary game! (Finally recognizing the importance of male function is, in effect, male liberation!)

Most flowers contain both male and female parts, although sometimes the sexes are in separate flowers on the same plant or on different plants. When males and females are separate, we sometimes see that the male flowers are bigger or more numerous than females, suggesting that more or bigger petals are very important for male function (i.e., sending pollen to the female flowers) in those species. This observation led to the idea that male flowers are competing with each other for the privilege of siring offspring, as often happens among male animals. It also became clear that showy petals could serve one gender-function more than the other, even in flowers that contain both, but this takes some clever experimentation to figure out.

There are several further complications to understanding why a floral display looks (or smells) the way it does. One factor is the availability of resources. In the case of our local fern-leaf goldthread, any given individual can switch from being entirely male, with only stamens, to being both male and female (hermaphrodite). If an individual contains female parts and produces fruit, that is a costly process, and that individual is not likely to produce female parts or fruits the next year; instead, it will produce only stamens and function only as a male. In this case, individuals are flexible, and can switch from one role to the other. In other cases, the response to resource limitation is genetically fixed, and whole populations exhibit resource-saving traits. For example, making a flower costs a lot of water (to expand the bud into a full flower), and in drier regions, populations of certain species conserve water by making smaller flowers.

Herbivores can exert tremendous pressure on flowers, sometimes in conflict with pollinator attraction. In wild strawberries, for instance, pollinators prefer large flowers, but so do destructive weevils, leaving the plant in a tight spot: make big flowers to attract pollinators or small ones to avoid the weevils? In certain species, flowers that are colored by anthocyanins (reds, purples, pinks) are better at deterring hungry insects, and where herbivorous insects are very common, whole populations of such species have anthocyanin-colored flowers instead of pale ones, which are found where the herbivores are scarce. Just how this works is unclear: There might be some direct protection by the pigments, or there may be an association between the genes for flower color and the ability of the plant to defend itself, or perhaps the same chemical pathways are involved in both. More to be learned!

In some cases, flower color is associated with the competitive ability of the plant. Certain colors are expressed where competition for space is intense, and others where competition from other plants is weaker. Apparently the same genes, or at least associated genes, control both aspects of the plant.

That is just a sample of the complex set of factors that can contribute to determining the floral display of a plant. I don’t mean to imply that all of them are operating in every case, but they (and others) need to be considered in understanding floral biology. These complexities are greatly understudied.