Flowery fun in Gustavus

an orchid show, and other floral delights

Lady’s slipper orchids are sometimes called moccasin flowers, referring to the shoe-like shape of the flower. One of the petals is modified to form an oval pouch with an opening on top. The edges of the pouch are rolled inward. A small shield-like structure hangs down into the back of the pouch and behind the shield are the sex organs. The flower offers no nectar to visitors, but at least some species have an attractive aroma.

Bees that visit these flowers enter the pouch, but the rolled-in edges keep them from crawling out. So, once in the pouch, the bees are obliged to crawl up behind the shield, in order to get out again. In doing so, they pass very close to the pollen-receiving stigma, leaving pollen from previously visited flowers, and the pollen-bearing stamens, picking up pollen on their bodies to carry to another flower. A very elaborate system for creating the next generation of lady’s slippers.

After pollination, thousands of dust-like seeds are produced. They are so small that they contain no nutrition for a developing embryo (this is true of orchids in general). Lacking a source of nutrition, the seeds have to rely on forming an association with certain fungi (mycorrhizae), in order to germinate and grow. Lady’s slippers are slow growing and take several years to reach the flowering stage.

There are dozens of species of lady’s slippers in North American and Eurasia. They belong to the genus Cypripedium. This name is derived from some ancient Greek words. Cypris is an old name for Aphrodite (a.k.a. Venus in Latin), the goddess of love and beauty. The ‘ped’ part of the name refers to foot or footwear, sometimes rendered as ‘sandal’. So Cypris/Aphrodite/Venus has a rather large collection of sandals in her wardrobe!

Lady’s slippers were familiar to me, from years spent in the Midwest, but I have never seen them in Juneau. So one of my hopes for a recent Gustavus trip was seeing these in bloom. We’d seen their leaves occasionally in the past, but the plants were not then in flower. On this June trip, with the help of a knowledgeable naturalist there, we located clusters of three species of Cypripedium. There was a large-flowered white one (C. montanum, or mountain lady’s slipper). A small-flowered, round white one with some brownish spots is called C. passerinum (sparrrow’s egg or northern lady’s slipper). A yellow-flowered species has often been classified as a subspecies of C. calceolus, but more recently botanists seem to consider it to be a separate species, C. parviflorum, the small yellow lady’s slipper.

June 22 Cypripedium passerinum Sparrow Egg orchid 2 resize
Cypripedium passerinum, sparrow’s egg lady’s slipper. Photo by Kerry Howard

Lady’s slippers and many other showy orchids are often collected from the wild by willful gardeners. But this practice has led to the near-extinction of some species. The slow-growing habit, low levels of pollination and seed set, and the need for mycorrhizal fungi make recovery of exploited populations slow and difficult. So these plants should never be harvested from their native habitats.

June 22 Cypripedium Yellow Orchid 2 resize
Cypripedium parviflorum, small yellow lady’s slipper. Photo by Kerry Howard

We found other orchids too. Tiny twayblades are much more common in Gustavus than in Juneau. They are pollinated by minute flies and wasps, as Darwin documented long ago. Coralroots and so-called rattlesnake plantain are common in Juneau as well as Gustavus.

Orchids were not the only flower show in town, however. Lupines created hills of blue on the beach dunes. Cow parsnips and buttercups brightened beachside meadows. Roses and irises added splashes of color. One meadow was thoroughly decorated with the small white inflorescences of Tofieldia, which is easier to say than the ponderous common name of sticky false asphodel. Sticky it is—the stem sometimes captures tiny insects. Apparently, some botanists thought the inflorescence resembled the European asphodel, which in Greek mythology grew in the meadows where the souls of the dead walked. Great stretches of forest understory were carpeted by the leaves of deerheart, which sent up its small white spires of flowers, and the nearly-luminous, wide, white flowers of bunchberry (one of my companions is alleged to have said that they lighted the way to the outhouse in the darker hours!).

Indian paintbrush provided the most stunning floral array. Here in Juneau we see some yellow-flowered ones and (especially at higher elevations, I think) a few red-flowered ones. But in Bartlett Cove we found a beach meadow simply covered with paintbrush flowers: yellow, red, orange, particolored, and every combination in between. Quite splendid.

Tricky flowers

…clever little arrangements for pollination

Most of our wild flowers are wide-open structures, just letting all the sexual parts hang out. Think of nagoonberry or cloudberry, asters, avens, silverweed, wild roses, geranium, anemones, and so on—all of these just present the sexual organs to whatever insect happens to land there. The smaller flowers of angelica and cow parsnip and their relatives do the same, but present the flowers in flat-topped bunches, making a good-sized landing platform for a visiting insect. It is then a relatively simple matter for an insect to walk around, picking up pollen from one flower and carrying it to another. Columbine and fernleaf goldthread dangle the sex organs loosely, downward or outward, where a visitor just bumps into them, when in search of nectar deeper in the flower.

Some of our flowers, however, are a bit more complex, requiring a visiting insect to do a little work or behave in a particular way. In these species, the sexual parts are typically enclosed within the flower—concealed in various ways. Here are some examples:

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Lupine. Photo by Bob Armstrong

Lupine: Bees pry open the flower, and when they depress the lowest, keel-like petal, out pop the stigma (to receive pollen, if the bee carried any) and the anthers (containing pollen to be deposited on the bee and carried to another flower).

Twayblade orchid: A visiting tiny bee or fly pokes into the miniscule flower, bumping into a projection that releases a sticky gob that pulls out clumps of pollen. The pollen is stuck onto the insect’s face or head until another flower is visited and the pollen is inserted there.

Violet: Down in the heart of the flower, the stigma is encircled by closed anthers, packed tightly together (the technical term is ‘connivent’—conjuring up mental images of conniving and scheming deviously (!). A visiting insect displaces the stigma, pushing it to one side and perhaps depositing pollen, and only then do the anthers open, releasing pollen to be picked up and carried away by the insect.

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Bog cranberry. Photo by Bob Armstrong

Blueberry, cranberry, shooting star, wintergreens (and tomato): Although the flowers differ in shape, all depend on what is called ‘buzz pollination.’ A visiting bee vibrates certain flight muscles (and buzzes), which causes pollen to shake down on the bee. If the bee already had pollen on its body, from another flower, it is brushed off onto the stigma.

Bunchberry/dwarf dogwood: the tiny flowers are clustered together, surrounded by white, petal-like bracts. Ripe flower buds open suddenly and the anthers explode their pollen into the air or onto an insect, when a tiny projection on one of the four petals is triggered, perhaps by an insect.

Lady-slipper orchid/moccasin flower: These flowers are doubly devious. They offer no nectar to insect visitors, who nevertheless prospect around inside the ‘slipper’, in hopes of a reward. But once inside that slipper, they cannot get out—except by squeezing through a tight opening at the back of the flower, where the sexual organs just happen to be located, convenient for pollen deposition and pick-up.

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Bog laurel. Photo by Bob Armstrong

Bog laurel: When the flower opens, the anthers are held in little pockets on the faces of the petals, with slim filaments linking them to the center of the flower. This species is normally pollinated by bumblebees: when the bee lands on a flower, the anthers spring out of their pockets and dust pollen on the bee. The springing mechanism is reported to be very sensitive, so perhaps even small insects, coming in search of nectar, can spring the anthers free, but it is unclear if the pollen would land on their bodies and if they would be effective pollinators.

All these clever little arrangements are a small sample of the ingenious contrivances for pollination exhibited by flowers in more southerly latitudes, about which whole books have been written. The world of flowers is far more complicated than one might expect.