On the Lemon Creek Trail

porcupine sign, hemlock observations, and singing birds

For weeks I’d been wanting to explore the Lemon Creek Trail, in hopes of enticing Parks and Rec hikers to go there again, after a hiatus of several years. I know the first part of the trail well—up over the saddle behind Home Depot, from many excursions to a dipper nest site that’s approachable from upstream (after a short bushwhack from trail to creek). But just over the saddle is a small swampy area and another small creek, and the continuation of the trail on the far side of the swamp eluded me.

So, one day in late March, I headed up the Lemon Creek trail with two friends, one with two feet and one with four feet. The trail was pretty icy, and we met a guy who had turned back, but our ice cleats proved themselves once more. Near the swamp, we crossed the little creek on a snow bridge, but –of course—missed the spot where the trail resumed.

So we floundered on down to some alder thickets close to Lemon Creek where the snow was still pretty deep. Soon we noticed a series of elderberry stems that had been nipped off. Sometimes the nipped-off stem was still there, and then we saw that the leaf buds had been nibbled away. Aha! So that’s what the porcupines were after. Cut off the whole stem to get a few bits of budding leaf. Most of the elderberry bushes in this area had been pruned by foraging porcupines. I have to wonder why they like the stuff—it smells bad (to me). I think elderberry has defensive chemicals intended to deter munchers, but porcupines seem to be able to deal with them, or else they are desperately hungry.

After plunging through the snow for a little while longer, I said that I had a faint memory that the trail should be a bit up the slope in the conifers. So we peered up the steep hillside, well decorated with devils club and, indeed, it looked like a trail up there. Up we scrambled, and there it was. Now I knew we could follow it back and find where it connected to the little swamp. It was a decent day, with just a little misty rain from time to time, so, having regained the trail, we went on. And the rest was ‘cake’. The trail is clear and easy to follow, probably because the research teams that go up to the glacier have kept it open.

Along the way, we commented that porcupines seldom seem to completely girdle the hemlock trees from which they eat bark; usually they just sample a patch on one side. No sooner had we said this than we came upon a twenty-foot hemlock that was completely de-barked all the way around from about one foot high to about fifteen feet above the ground. What made that little hemlock so tasty, apparently? It was outcompeted (for light) by its much taller neighbors, so maybe it didn’t have a lot of energy to allocate to defensive chemicals.

We trudged and slid along, eventually dropping back down to a broad sand flat with lots of alders and the remnants of an old log bridge. Just upstream from here, the creek makes a ninety-degree turn, and so does the trail, which goes on up the valley.

Several years ago, Parks and Rec used to be able to walk up the road through the gravel pit on the opposite side of Lemon Creek, cross a bridge, and thus get to the wooded valley that comes down from the glacier. But nowadays, one gets to this point by almost two miles of trail from the trailhead behind Home Depot. After numerous side excursions to look at things, by the time we reached the sharp angle in the stream, it was time to turn around. So we perched on a log to share a snack while gazing at the creek and wistfully contemplating another day when that upper valley could be explored.

Our return trip was uneventful, although the snow bridge that held both of us on the outward-bound trip only held one of us on the way back. But at least I didn’t get my feet wet in the little creek!

The conifers were full of talkative pine siskins and a few crossbills. Juncos flirted around in the brush by the big sand flat. Varied thrushes sang all day. Kingfishers rattled up and down the stream, no doubt checking out cutbanks in which to dig a nest hole. A dipper put on a concert down in the creek. Best of all, we heard our first winter wrens trilling enthusiastically. But technically, we can’t call them winter wrens any more. The taxonomists have decided that the western winter wrens are genetically distinct from winter wrens in the east (and Europe, where they are called The Wren). Although the plumage differences are subtle, and the songs are not very different, the calls are reported to be distinctive. So now our wrens are known as Pacific wrens.

All in all, a good day. Mission accomplished, most pleasantly. Now to see if Parks and Rec will try this trail, come summer.

On the water

a whale watch trip stirs up questions

I don’t get to go whale-watching very often, but when I do, I usually see something interesting and new questions frequently get stirred up.

One trip gave us a good view of humpback whales doing their locally famous bubble-net feeding. Most of us here have seen this behavior at one time or another, but somehow it has not become ‘old hat’. How does a group of whales decide which one will create the rising, circular curtain of bubbles that rings a school of little fish? How did they invent this foraging tactic in the first place? Did it really originate here, and get carried to Prince William Sound whales by a wandering Juneau whale? How do they coordinate the upward rush of several whales through the panicking fish and avoid crashing into each other?

Another trip brought a troop of Dall’s porpoises, cavorting around the bow of the ship. The group grew, as additional individuals came zooming in from who knows where. They played there for some time, to the great delight of all on board. Then they disappeared, apparently on some magical signal; suddenly they were simply gone, vanished out of sight. Why did they all gather by our ship? And why did they go?

Then, in early September, we watched a small pod of orcas cruise by Little Island, where hundreds of Steller’s sea lions, of all sizes, had hauled out. Even the few sea lions that happened to be in the water a few feet from their dry confreres on the beach did not seem to be alarmed at the orcas passing nearby. Mammal-eating orcas don’t use their sonar to find prey, because mammals can hear the beeps. So we thought that these must be a resident, fish-eating bunch of orcas, using their sonar to find fish and therefore no threat to the sea lions.

As the orcas went on down along Ralston Island, we learned that this was actually a group of transient, mammal-eating predators, identified by a known mark on one of them. Nevertheless, no prey was visible and they acted (to our eyes) as if they were hunting fish: sudden, brief changes of direction and quick dives. This led to the question of whether mammal-eating orcas might sometimes snack on fish as well.

Then a small band of juvenile sea lions came into view from the opposite direction, seemingly oblivious of the jinking-around orcas—until the two groups of animals were very close. Then the sea lions really freaked out, caught between the rocky shore and the orcas. Much frantic splashing and churning about! As the orcas placidly went on their way, the sea lions calmed down and swam toward Little Island. What was going on here? Mammal-eating, transient orcas with already full stomachs? Just fun and games for the orcas? Mistaken identification by the sea lions?

Later that same afternoon, we encountered a scattered group of humpbacks doing nothing very exciting. But alongside our boat there appeared a solitary sea lion with something in its teeth. That sizable something was tossed and thrashed about until it was just a rag (and a few loose bits for the attending gulls). Finally we got a closer look and saw tentacles with sucker discs, just before the whole thing disappeared down the gullet of the sea lion. The octopus was caught at depth of over four hundred feet, not a very deep dive for a sea lion.

Orchids

extraordinary diversity and behavior

Humans have been fascinated by orchids for ages. When we think about orchids, most of us visualize the flamboyant, exuberant, gaudy floral displays produced chiefly by tropical species or by the activities of avid orchid breeders. Fair enough, but…

All that flamboyance and showiness evolved because each kind of orchid flower is very complex and adapted to particular pollinators. Most of the pollinators are insects, but a few are pollinated by hummingbirds. Each kind of flower is visited, typically, in a very specific way by its pollinating animals. Although some orchids do not require a pollinator but, rather, simply pollinate themselves, the majority set seed after the visit of a pollinating animal. Different kinds of orchids offer different rewards to pollinators, usually nectar, but sometimes special oils or fragrances. Some reward-less orchids rely on fooling visitors, by just looking like they might have a reward and so attracting naïve insects, or (most famously) by looking like a female insect and fooling the male insects into trying to copulate with the flower.

Orchids have actually gone a bit crazy. There are probably over twenty-five thousand species; taxonomists are not sure just how many there are. But there are way more orchids than all the birds and mammals in the whole world, and more orchids than any other kind of flowering plant except perhaps the aster and daisy family. Although they are most common in the tropics, orchids can be found almost everywhere except Antarctica and the very High Arctic, occupying almost any habitat, including on other plants; one even lives entirely underground.

Southeast Alaska has its share of orchids: as near as I can tell, we have about twenty-six species in nine or ten genera (genera is the plural of genus, a taxonomic unit that clusters similar species together). The numbers are a bit uncertain because taxonomists often have differing opinions on how to demarcate the species and how to cluster them. In this space, I intend to introduce each genus that’s found in Southeast, with a bit of information about its name and its biology. Most of our orchids are not as gaudy as their southern relatives, but they share some nifty adaptations with their gaudier cousins. Because I like to know how things work, I’m including information on how the flowers function, that is, how they control the visits of their pollinators—which, after all, is what orchids are famous for!.

Before I launch a discussion of our orchids, it is useful to explain a few things that apply to all or most orchids. By doing so, repetition can be avoided or at least reduced. And, by the way, in case you were wondering, the name ‘orchid’ comes from the Greek word for testicle, because the bulbous roots of some species reminded someone of male gonads.

All orchids produce huge numbers of minute, dust-like seeds that lack stored nutrients for seedling germination and growth. Therefore all seeds depend on forming associations with particular fungi (mycorrhizae) that bring in nutrients from decaying organic matter or from other plants. Finding the right mycorrhiza is a chancy business, and most seeds just die. If a seed finds the right mycorrhiza and germinates, most orchids plants eventually produce green leaves that can photosynthesize carbohydrates, and thus they can live somewhat independently. But some orchids have no greenery and are forever dependent on their mycorrhizae.

I will spare you (and me!) the fine details of the intricate arrangements of orchid flowers, which can be bewilderingly complex. But I will mention one very peculiar and mysterious thing: while an orchid flower is developing, it often (for some odd reason) rotates a hundred and eighty degrees on its axis, so what was up is now down. That is rather mysterious in itself. In one species of the genus Malaxis (at least in the European populations of a species that we have in our area), however, the rotation is a full three hundred and sixty degrees, so what was up is again up. I find this most peculiar—if the goal is to have ‘up’ be ‘up’, why rotate at all? Darwin noted this, and then, to confound all logic, saw that the ripe seed pod UNtwisted itself by three hundred and sixty degrees. Very peculiar. And all of that begs the question: Do those that twist only a hundred and eighty degrees also untwist when seed ripen?? It is all very strange!

Most orchids disperse pollen in clumps, rather than as loose collections of powdery, separated pollen grains (as in most flowers). The clumps of pollen grains are generally held together by sticky material and elastic threads, and sometimes several clumps are stuck together. The clumps are called pollinia. Although some other flowering plants (such as milkweeds) produce pollinia too, this habit is relatively unusual. When they pick up a pollinium, pollinators then carry many pollen grains at a time. This would seem to be very efficient, but actually the seed production of many orchids is limited by too-few pollinator visits.

OK, now for our Southeast orchids. I’ll start with the smallest and least conspicuous, dealing with each genus in turn, working up to some local beauties.

Listera. The genus is named for a seventeenth century English naturalist (Listera). These diminutive plants are known as twayblades, for the two broad leaves flanking the stem. There are four species in southeast, although two are rare. I have seen good numbers of two species along the rainforest trail near Bartlett Cove, and they should be quite widespread elsewhere in Southeast.

The nectar-bearing flowers are tiny, only a few millimeters across, and they are pollinated by equally miniscule insects such as dance flies, fungus gnats, or minute wasps. Darwin thoroughly studied the pollination mechanism of an English species of Listera, and ours apparently work the same way. When an insect touches a beak-like structure in the flower, a drop of very sticky liquid explodes from that structure, catching the tips of the pollinia and gumming them to the head (often the eyes) of the visiting insect. The sticky fluid hardens almost immediately, so the insect flies away with pollinia stuck on its head. After firing the sticky liquid and the pollinia, the female receptive surface (called a stigma) is exposed and ready to receive a pollinium from the next insect. When an insect bearing a pollinium on its head visits a flower whose stigma is exposed, the pollinium contacts the sticky stigma, so pollen is pulled away from the insect and pollination occurs. For all of this to happen, the beak-like structure actually moves, first to put the pollinia in position to be picked up by the exploding drop, and then to expose the stigma so another insect can deposit pollen.

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frog orchid. Photo by Bob Armstrong

Coeloglossum. The genus name means ‘hollow tongue’; I have not learned the source of this name; one idea was that it derived from the spur that holds nectar, but since this is shaped like a tiny sac and is not at all tongue-like, this name is puzzling. The common name is frog orchid, but it doesn’t look like a frog (to me), so that name is also a puzzle. This is reportedly a short-lived species, able to flower during its first year above ground and seldom living more than about three years. The flowers can be pollinated by small insects of various sorts, but details of how the flower works are not available; self-pollination is possible.

I’ve seen frog orchids on Gold Ridge, where they are not common. Although they can apparently produce many greenish flowers on each stem, the ones I’ve seen have all had only a few flowers on each short stem. These plants on Gold Ridge are at risk by being trampled by the many visitors that walk above the tram.

Malaxis. Once known as Hammarbya, the newer name of Malaxis comes from a Greek word meaning soft or softening, referring to the soft leaves of some species. The common name is, sadly, adder’s mouth orchid or adder’s tongue. Someone must have thought the flower resembled the front end of a poisonous snake (it takes a very unusual imagination!). There are two species in Southeast, mostly in bogs.

The tiny (less than two millimeters) flowers are yellowish green. They have nectar and a sweet odor, which attract very small insects, such a fungus gnats. Darwin studied one of our species, which also occurs in Eurasia. He observed that a sticky drop holds the ends of the pollinia, and when an insect enters the narrow opening of the flower, it runs into that sticky drop and pulls out the pollinia (on lower, front part of its thorax) when it flies on. When the insect then enters the next narrow flower, the pollinia are pulled off, in contact with the stigma. Apparently this species does not self-pollinate but requires an insect to bring pollen from another plant of the same species, achieving cross-pollination; however, the second species in our area may often self-pollinate.

Malaxis orchids reportedly have the peculiar but useful habit of vegetative propagation by means of little bud-like structures on the leaf tips; these little structures can sprout and grow into new plants.

dance-fly-in-early-coral-root-orchid-blossom
Dance fly in a coralroot orchid blossom. Photo by Bob Armstrong

Corallorhiza. There are two species of these coral-root orchids in Southeast. Both names describe the appearance of the roots, which are thought to look like branching corals. Both species produce fairly tall flowering stems with multiple flowers, either pink or yellow. Both lack any green pigment, so they cannot produce their own carbohydrates and are therefore dependent on their mycorrhizal associates for nutrients.

Both species are visited by small insects, including flies and wasps and bees, that can carry some pollen from plant to plant. However, most seeds are apparently produced by self-pollination, without a visit from an insect bringing pollen from another plant.

The pink-flowered species is often seen in conifer forest, but the yellow-flowered one seems to prefer more open, often deciduous woods.

Goodyera. The genus bears the name of a seventeenth –century botanist. The common name is entirely ridiculous; it is called rattlesnake plantain, although it has nothing to do with snakes of any kind nor is it a plantain. Because the leaves are sometimes mottled with white, some early pioneers may have been reminded of snakeskin and thought, by simple association, it could be used to treat snakebite. However, there aren’t many rattlers where our species lives, so the name seems doubly foolish.

One species of Goodyera grows in our forests. The flowers are white, borne on a tall spike. Each flower is first male, with mature pollen, and then female, with a sticky, receptive stigma (this sequence is called protandry, or first-male). Internal parts of the flower rearrange themselves slightly to better expose the stigma after pollen is removed. Pollination is reported to be accomplished by bumblebees, which first visit the older, female-phase flowers low on the spike, depositing any pollinia they may carry. Then the bees move up the spike, reaching the male-phase flowers and picking up pollinia, on their heads or tongues, to carry on to the next plant. Thus, seeds are typically produced by cross-pollination between different plants.

orchid-Pam
Platanthera. Photo by Pam Bergeson

Platanthera. There are at least eight species in Southeast. Some produce white, very aromatic flowers, while others make greenish flowers, but all bear the flowers on an elongated stalk. These orchids formerly were classified as species of Habenaria, from the Latin word for strap or rein (probably because one of the main flower parts is flat), hence the common name of rein orchid; an alternative name is bog orchid (although some also grow in wet forests). The current genus name seems to mean ‘flat flower’, perhaps referring to the same flower part.

Bog orchids are pollinated by a variety of insects, some mostly by moths or both moths and butterflies, others probably by bees, some by small flies and mosquitoes, and some by almost any insect of the right size and inclination. Our white, aromatic bog orchid is pollinated primarily by moths, at night, and our green bog orchid may have several possible pollinators. Certain species exhibit regional variation in the length of the nectar spur, odor of the flower, and the type of insect pollinators, even within the same species.

Platantheras present nectar in a nectar spur, which is visited by a foraging and pollinating insect, when it enters the flower in the proper way, from the front, and encounters the sexual parts. But at least some species also produce small dollops of nectar on other parts of the flower, perhaps to increase the allure of the flower to insects that subsequently enter the flower in the proper way.

The pollination mechanism is simple: the insect shoves it head into the flower, reaching into the nectar spur, and bumps into the sticky parts of the pollinia, which then attach to the eyes or tongue of the insect. Although cross-pollination is usually the norm, many of them may simply self-pollinate, if no pollinator visits them.

Piperia. Named for an American botanist, two species occur here; they are widespread but rare. They are similar to and sometimes classified with Platanthera, but sometimes they are classified in their own genus. They typically live in open woods. The flowering stem bears a number of small, green or white flowers that are reported to be aromatic especially at night, when they are pollinated by moths. A visiting moth can poke its head and tongue a short distance into the flower, and pick up pollinia on the tongue; an older flower is more open, and a visiting moth bearing pollinia can insert its head far enough to deposit pollinia on the stigma. Piperias are thought to be chiefly cross-pollinated.

Spiranthes. As the name suggests, the flowers spiral up in a tall spike. The common name is ladies’ tresses, because someone thought the inflorescence looks a bit like a woman’s braids. The white flowers are pollinated principally by long-tongued bumblebees. As in Goodyera, the flowers are typically protandrous (first male, then female), and when nectar-foraging bees work their way up the spike, from older flowers to younger ones, the last flowers they visit stick pollinia onto the bees’ tongues. As observed in detail by Darwin on a similar species, the pollinia are attached to a sticky disc, whose stickiness is activated by the bee’s tongue as it passes through the narrow opening to the pool of nectar. When the bee’s tongue is withdrawn, the pollinia are pulled out. On older flowers, the internal parts of the flower have been rearranged slightly, widening the opening where the bee inserts its head and exposing the receptive stigma. Flowers are usually out-crossed, but when there are few pollinator visits, male and female phases of each flower may overlap more, and some self-pollination may occur if a bee does visit. There is one species in Southeast. A study of our species on Vancouver Island, B. C. found that flowers received abundant bee visits and set seed accordingly, but visitation rates and seed production have not been studied here, where bee populations may be less dense.

June-22-Cypripedium-passerinum--Sparrow-Egg-orchid-2-resize
Sparrow’s-egg orchid. Photo by Kerry Howard

Cypripedium. The genus name of ladyslippers or moccasin flowers comes from classical mythology. It refers to the foot of Aphrodite (or Venus), who was formerly called Kypris. Presumably an inventive observer imagined that the foot of a goddess of love might wear a floral slipper. We have at least one species (with white flowers), mostly in open woods in scattered locations, and two others may creep in to the northernmost part of Southeast.

Ladyslippers have no nectar, but they are often aromatic. The flower acts like a trap. When a small bee enters the pouch-like slipper, it cannot get out the same way because of the slippery sides and in-rolled margin of the pouch. So the bee has to exit through the upper part of the flower and, in so doing, it passes by the sexual parts of the flower. In general, Cypripedium pollen is very sticky and readily adheres to the crawling bee, which picks up pollen as it leaves the flower. When the bee enters and exits another ladyslipper, it encounters the female parts first, brushing off pollen on the stigma.

Some species of ladyslippers can become dormant for as long as three to five years, not showing above-ground shoots at all during that time. Prolonged dormancy can be induced by stress, perhaps from a bad growing season or the cost of making many seeds. These dormancy periods sometimes presage mortality, but in other cases, the shoots come up again and the flower blooms after its rest period.

fairyslipper-orchids-by-bob-armstrong
Calypso. Photo by Bob Armstrong

Calypso. The common name of fairyslipper was no doubt inspired by its delicate and lovely shape, suitable perhaps for an ethereal, light-footed creature. The genus name comes ultimately from the Greek word for concealed and more immediately from the mythological goddess, Calypso. She was a beautiful nymph that lived in the forest. According to Homer’s Odyssey, she found Ulysses (Odysseus) when he was shipwrecked on her island, and she kept him for seven years.

The showy, pink-purple flower, usually one per stem, is said to be very aromatic, but it has no nectar. Bumblebee queens are the principal pollinators. Naïve queens (with no previous experience with this flower) visit calypsos but each queen soon learns that there are no nectar rewards to be found there, although the aroma might suggest otherwise. Such pollination by deception is characteristic of many orchids. Supposedly the queen bees learn quickly, so many calypsos are visited only once, and pollen may be removed but not deposited on another flower. Some researchers suggest that the slight variations in color and aroma that calypsos exhibit might facilitate fooling the bees into visiting more than one flower and accomplishing pollination.

The bees enter the open flower but discover no nectar and then back out. When they back up, apparently they hunch their backs and if, on the back of the thorax, they carried a pollinium from a previously visited flower, it gets brushed off on the stigma. A little farther toward the front of the flower, the backing-up bees encounter the pollinia of that flower, which in turn sticks to the back of the thorax, to be carried to another flower—unless the bee has learned its nectarless lesson. Calypso flowers may last more than eight days if not pollinated, but they wither in three or four days if pollination was successful. Apparently, fruit productions in calypso is generally poor, reflecting a low level of successful pollination.

We have one species of calypso here. I have seen it rarely, mostly in open, relatively dry areas. It is a temptation to pick Calypso flowers when one finds them, just because they are so lovely. But that seemingly simple act is likely to kill the plant, because the little, plucking tug can break the extremely delicate roots. So please don’t pick them!

There you have our orchids, and a lovely array it is. It is best not to try to transplant them, because many are delicate, and some are rare, so they should be left where they find themselves naturally. We can enjoy them in their natural places.

Thanks to Mary Stensvold and Ellen Anderson, USFS botanists, who provided helpful consultation.

Parasitic flowering plants

trouble underground

When we think of parasites, we usually think of tapeworms, ticks, fungi, and assorted micro-organisms. But the world of flowering plants provides some interesting examples of a botanical version of parasitism, in which one plant extracts nutrients from another. We have two quite conspicuous and common kinds of flowering-plant parasites: hemlock dwarf mistletoe (Arceuthobium campylopodium) and northern ground cone (with the resounding name of Boschniakia rossica). Both of these species are entirely parasitic (or almost so). They derive all or almost all of their nutrients from their host plants and are unable to survive without a host.

You may have noticed the ‘witches brooms’ of gnarly, tangled branches that are the result of a mistletoe infection. The mistletoe alters the balance of growth hormones in hemlocks (and sometimes other species), causing the ‘brooms’. Male and female mistletoe plants are separate, with very small, inconspicuous flowers. Pollination is mostly by wind. When the seeds mature, they are discharged explosively; they are capable of travelling ten yards or more. Because they are sticky, they adhere to other branches or trunks and start new infections. This species has been reasonably well studied, because heavy infestations decrease the economic value of the timber.

 

The ground cone pokes up above ground in June. All we see is the cone-like inflorescence of tightly packed, brownish flowers; the rest of the plant is underground. Ground cone is commonly parasitic on the roots of alders, and sometimes other species, including blueberries. Various insects may visit the flowers and accomplish pollination; occasionally we have seen bumblebees probing the flowers. The seeds are minute and very numerous. The biology of this species apparently has not been studied in detail, as I can find no scientific papers on the subject, but the medicinal uses of this plant are reported to be many. We do know, from local observations, that bears frequently dig up and eat the underground base of the flowering stalk.

In addition, all orchids depend on their mycorrhizae (fungal associates) at least at some time in their life history. Some researchers consider the relationship to be mutualistic, with both participants gaining some advantages, and that eventually may be the case when the adult orchid develops green leaves and can provide carbohydrates to the fungus in return for soil nutrients. However, other researchers refer to mycorrhizal associations as a parasitism by the orchids on the fungi. This seems especially applicable in the case of orchids that develop little or no green tissue as they mature, so they can contribute nothing to their fungal associates. We have two species of the genus Corallorhiza (coralroot), one of which has no green tissue at all, while the other has a little and so can make some carbohydrates. They are both parasitic on fungi for all of their lifespans, but the relationships are even more complex: they can indirectly parasitize green plants through their fungi, which attach to the roots of trees and shrubs (which have their own mycorrhizae), and draw nutrients from those hosts.

Less well known are the so-called hemi-parasites, half parasitic and half independent. They have chlorophyll and can synthesize carbohydrates, but also commonly latch on to other plants and capture some nutrients from these hosts. We have a number of hemi-parasites among our local flowers.

The plant called yellow rattle or rattle box (Rhinanthus minor) grows in open areas at low elevations. This species is capable of parasitizing the roots of many other herbaceous species, including grasses. A single Rhinanthus plant can attach itself to the roots of several other plants. Some plants, however, are able to resist invasion by the roots of the parasite. Rhinanthus plants clearly benefit from the parasitic connections, growing and reproducing better if they are connected to a host. Some hosts, such as legumes, are better than others in providing the parasite with nutrients. In addition, the parasite can take up defensive chemicals, such as alkaloids, from the host, and thus reduce the risk of herbivory. The effects on the host plants are negative, because many of their nutrients are drained away by the parasite; parasitized hosts have decreased growth and reproduction; the negative impact is greater in some hosts than in others. There are indirect effects of Rhinanthus parasitism too: parasitized hosts have lower ability to compete with other plants in the community, and lower ability to recover from herbivory, which then affects the relative abundance of various species in the entire community.

Pink-Indian-Paintbrush-1
Photo by Bob Armstrong

There are three species of Indian paintbrush (Castilleja) in Southeast, but only one has been studied much, and those studies were conducted elsewhere. In general, members of this genus grow better, flower more, and resist herbivory better, when they are connected to a host plant. Legumes seem to be better hosts than other plants, and two or more hosts may be better than one. When a parasitic paintbrush plant dies and decays, decomposition is accelerated, and co-occurring species have increased productivity, which may counter the usual negative effects of the parasite to some degree.

The genus Pedicularis—the louseworts–has about five representatives in our area, which have not been studied directly, as far as I can tell. In general, the negative effects of parasitism by different species of lousewort may vary among host species, and different louseworts have different host preferences. Some louseworts are reported to have mycorrhizal associations too, collecting nutrients via the fungal connection in addition to the usual direct parasitism.

Clearly, the world of the parasitic flowering plants is complicated, and it gets more complex as more studies are conducted. All those pretty (and not so pretty) flowers are intricately involved with many ecological interactions, and what we see above-ground is only a small part of the story.

Peterson Lake Trail

slime molds, a berry cornucopia, and a beautiful poison

One bright, sunshiny day in mid August, we checked out the Peterson Lake trail, which is about four and a half miles long, and ends at cabin by the lake. There were rumors of recent trail improvements on the first three quarters of a mile. Indeed, there’s a section with a new base layer of angular, ankle-twisting cobbles, eventually to be covered by finer gravels; then there’s a section of packed dirt and, just before the big waterfall, a smooth section of finished trail.

After the big waterfall (where the steelhead have to stop, in the spring), the trails goes on as it has for years, with a section of packed dirt and slippery ‘corduroy’ logs and then boardwalks through the muskegs. At the Mile 2 marker, a long stretch of mud and roots winds through the forest until the lake finally appears.

The forest was very quiet on this day and no birds were evident, so those of us who are interested in natural history focused nearer the ground. A black slime mold had developed on a log: thousands of individual, independent cells had been feeding on bacteria and fungi in the soil, but now they had gathered together in a single mass for reproduction. Some of the cells will produce spores, while others serve as support structures for the spore-producing individuals. I wonder how they decide which cells will make spores!

The muskegs were dotted with several kinds of ripe berries, including black crowberries, bog blueberries, red bunchberries, and orange cloudberries. I was interested to find a large colony of timberberry in one of the muskegs, with several stems bearing the orange fruit. Timberberry is sometimes called pumpkin berry or, for no apparent reason, bastard toadflax—a name more correctly applied to a different species, but still for no known reason. The name game gets quite confusing, because this plant had been classified in two different genera at different times by different taxonomists. Sigh. The most interesting thing about this plant is that it is a hemi-parasite, drawing some of its nutrition from other plants while also having its own leaves. This is a very versatile parasite, capable of using many host species, such as spruce, alder, willow, currant, bunchberry, horsetail, asters, lupines, and dozens of others.

timberberry--2-David
timberberry. Photo by David Bergeson

The lake level seems to be maintained in part by beaver dams at the outlet. After poisoning many of the resident fish some decades ago, the lake was stocked with juvenile rainbow trout (in the 1960s). A boat by the cabin gives ready access to all parts of the lake.

Along the trail, we noted several late-flowering monkshoods, one of our loveliest wildflowers, which grows at many elevations around Juneau. The complex, bumblebee-pollinated flower is usually a rich purple, although sometimes the purple is streaked with white. A fascinating feature of this plant is that ALL parts are reported to be very poisonous, but perhaps especially the roots and seeds. Eating even a tiny amount of this plant is likely to cause intense gastro-intestinal distress, followed by cardiac and respiratory failure if not treated immediately. And if you handle the plant more than casually, for example by picking leaves or breaking off the stems with your bare hands (not merely brushing by it as you walk), your skin can absorb the poisons. You are then likely to suffer the negative cardiac and respiratory symptoms, but without the gastrointestinal calamities.

The poisonous properties of monkshood have been known for centuries, and extracts of the plant have been used to make poisonous arrows for hunting or warfare, among other deadly uses. On the other hand, as is true of many plant poisons (think of digitalis, for instance), monkshood has also been used medicinally, in small, careful doses. It is a food plant for the caterpillars of several species of moth, which clearly have evolved physiological means of dealing with the poisons. And the bumblebees that pollinate the flowers either find a way to cope or else perhaps the nectar and pollen has less of the poison. Monkshoods are popular garden plants, but it is obvious that gardeners must handle this plant with great care!

One thing leads to another…

following the bear over the mountain

I like to take a walk just to see what I can see, like the bear that went over the mountain, in the old song. You never know what might be found, until you look. Keep looking, and something of interest will turn up. Here’s a recent example—nothing stupendous, but a small story that started simply by noting something unexpected, checking it out, and seeing what developed.

A friend and I walked along a small stream, talking (of course) and looking at wind-throws and mosses and whatever. We spotted something yellow, bright yellow, floating in a backwater. We detoured down to the edge of the stream and checked out the odd yellow object. It was an uprooted skunk cabbage plant; there was the rootstock with many thick roots and two shoots ready for next spring, a green one, partly eaten, and a yellow one that would be next spring’s flowering stalk. I’d never seen the full rootstock before (bears like to dig it up and eat it) nor all those roots, so that was new and interesting. But why was it left there?

As we pondered the floating skunk cabbage, we noted a pile of sticks, just a little way down the shoreline. We quickly saw that this was a winter cache made by beavers—sticks neatly cut and stacked. The cache held branches and twigs of several species: lots of rusty menziesia, some alder and blueberry, and a few hemlock branches. An unusual assortment, in my experience. When they can get them, beavers really like cottonwood and willows, but these were not available in this area.

If there is a cache, there should be a beaver lodge nearby. But we could find no conventional lodge built of a mound of sticks and mud. Maybe these beavers lived in a bank burrow, under the roots of a big spruce tree.The beavers had built a small dam a short distance downstream of the cache. By raising the water level, they would keep the entrance to their living quarters underwater, protecting their ‘doorway’.

As we meandered along upstream, after our detour, we began to note the stubs of cut-off shrubs in several areas. These cuts, and those on the cached sticks, looked quite fresh. Soon we saw several narrow trails running from the creek-edge up into the woods, where there were more cut stubs. A few cut branches had been left along the trails, perhaps to be hauled later to the cache. Some of these trails had been made after a snowfall, and there were dollops of mud and footprints as evidence of recent use. Beavers had used some of these trails repeatedly, so they were well trampled. But we could find a number of clear footprints of beavers’ hind feet. And otters had used the trails too.

These signs obviously meant that the beavers had been active outside of their winter quarters, even though they had a cache. This is known to happen, but usually beavers spend the winter months snug in their houses, the adults living partly off stored body fat, and the young ones, still growing, feeding on the cache. If you stand, very quietly, close to a beaver lodge, you may hear the family members talking to each other, murmuring and chuckling.

There you have it—a simple story, but very pleasing to see how one thing led to another. The story expanded from a single basic observation of something that seemed out of place into a picture of family life and uncommon winter activity. Would we have seen those small trails and footprints as we walked along? Certainly. But we would have missed the skunk cabbage and the cache and the invisible lodge. So the picture would have been sorely incomplete.

Mustelids

weasels and their kin

One of the treats of a snowy winter is wandering around looking for animal tracks. When I counted up the species for which we’ve found tracks, I saw that one taxonomic family was disproportionately represented—the Mustelidae. Five species of mustelids are likely to leave tracks in snow in our region: ermine, mink, marten, river otter, and wolverine. I’ll first present some basics about mustelids in general, and then some specifics about each of these five species.

Mustelids are a widespread family, occurring on every continent except Australia and Antarctica. There are over fifty-five species, ranging in size from the diminutive least weasel, weighing as little as one or two ounces, to the sea otter, reported to reach over a hundred pounds. They tend to have relatively long, thin body shapes, although some, such as badgers, are stockier; legs are generally short. The claws do not retract (unlike most cats), but again there is an exception: the claws of the fisher are partially retractable. Males are generally larger than females of the same species; their home ranges are larger and tend to overlap those of several females.

They are typically carnivores, preying on a variety of small or middle-sized animals, and sometimes scavengers, although some, such as marten, also eat fruit (and serve as seed dispersers). Much of their ecology is related to availability of food: population abundance, litter size and survival, frequency of reproduction, rate of maturation of juveniles, adult survival (starvation is reported to be a common cause of death in wild populations).

Along with males of many other placental mammals, male mustelids possess a baculum or penis bone. The size of this bone in different species has been suggested to relate to the length of the copulatory act: long bacula are correlated with long copulations. Extended copulations are not generally possible when penile erections depend entirely on hydraulics, i.e. blood pressure. This begs the question of when and where long copulations are adaptive or, conversely, when and where short ones are adaptive. As you might imagine, the subject has attracted some discussion but with no definitive answer.

Most mustelids also share a reproductive habit that (to humans) seems odd: After copulation, the fertilized egg divides just a few times and then rests; it does not implant immediately in the uterine wall, so no placenta is formed and the embryo does not develop further for some time. The delay of implantation lasts several months, during which the few-celled embryo just floats around in the uterus. Eventually, however, it does implant, a placenta develops, and active gestation (just a few weeks long) begins. Thus, the time of mating and the time of active pregnancy are well separated, and birthing is therefore postponed to a season well after the mating season. Delayed implantation is typical of numerous other mammals, including bears and seals.

The adaptive value of a seasonal separation of mating and birthing is often discussed. Most explanations address the importance of rearing young at times of year when food and other conditions are optimal.

This leaves unanswered the reason(s) why mating occurs so long before the season for rearing offspring, and I have not discovered good explanations. In some cases, other aspects of the life history may have created limitations on the convenience of getting male and female together; for instance, bears hibernate for the winter and sexual encounters shortly before birthing are not likely, summertime is surely more convenient; or males take advantage of freedom from child care to go roaming and foraging while females tend the young. I’d like to find a serious analysis of the conditions that favor the seasonal separation of mating and birthing.

Here are a few interesting factoids about our resident mustelids:

River otter—They are very aquatic, eating mostly fish, other aquatic animals in open water or tide pools, and sometimes capturing floating birds from underwater. They can dive to about twenty meters, staying under up to four minutes or so. Being heavy-bodied, they must tread water or scull with the tail to stay afloat. Otters are reported to forage cooperatively in some locations (e.g., Prince William Sound). Otters often travel overland between bodies of water, sometimes sliding over the snow. Their home ranges are said to be smaller on the coast than in the interior, presumably because food sources are more abundant. Otters usually mature at age two years.

Wolverine—They often favor remote areas but use a variety of habitats. In winter, this large mustelid mostly forages by scavenging carcasses left by other predators; its powerful jaws can crack the bones of moose. It is sometimes said that wolverines are too big to survive very long on small prey, too small to kill large game animals regularly, and too slow to chase fast prey. So scavenging becomes a good way to feed. In summer, carrion is less available and wolverines eat more small mammals and birds. They commonly den under deep snow in alpine areas, but commonly travel widely (many miles) to find food. If they get lucky, they will cache surplus food in a handy location. They are slower to mature than our other mustelid residents, usually maturing when three to five years old.

marten-5-Matt-Knutson
marten. Photo by Matt Knutson

Marten—Denizens of old-growth and mature forests, they are highly arboreal. They commonly feed on small mammals, as well as birds, eggs, and carrion, and are said to need the equivalent of at least three voles per day. However, they can also kill hares and marmots. They mature at age one or two years, depending on food supply. There are two species in Southeast; detailed genetic studies have shown that Kuiu and Admiralty islands are home to a distinct and strictly coastal species (which also occurs on Haida Gwaii and Vancouver).

Ermine—They eat almost anything that moves and need to eat almost continually; they are good swimmers and climbers. They make cozy nests, often usurping the nest of a prey mammal (after eating it), even lining the nest with fur of the prey. Well-insulated resting places are necessary for this small, slender predator that needs this help to keep warm in winter. Sometimes they cache their prey near the nest. Juvenile females can become sexually mature while still in the natal nest, at an age of only one or two months. So, when their mother mates after giving birth (which is the custom with these animals), sometimes the same male will fertilize her daughters as well! They have a short life span in the wild, often living less than two years. Ermine are represented by three distinct genetic lineages in our area, and one of them, with a very limited distribution, is considered to be of conservation concern.

Mink—Comfortable on land and in water, they eat fish, crayfish, various other small aquatic critters, and birds—they are said to be especially fond of bird eggs. They make short dives but usually forage in the shallow water or on land. Mink (and wolverines, ermine, and marten) are adept at climbing. They, like squirrels, are able to descend from a tree rapidly and skillfully, because they can rotate their hind ankles so the claws engage with tree bark. They breed as yearlings, and seldom live longer than three years in the wild.

The populations and historical geographic ranges of marten, wolverine, and river otters in North America have been seriously restricted by human activity: habitat loss including deforestation, over-trapping, pollution (especially otters), reduction of their prey populations. In some cases, reintroductions have restored local populations.

Footnote: (There are three other mustelids in Alaska but we don’t generally see evidence of them here. Least weasels live up north and do not occur here. Sea otters live in the sea, yes, and seldom come ashore. Fishers have only rarely been recorded in Southeast and, in any case, are very elusive.)