Japanese Knotweed (Fallopia japonica) was introduced from Japan in the 1800’s as an ornamental; it was widely cultivated, escaped and is now well established throughout the Northeast. The World Conservation Union lists Japanese Knotweed among the top 100 worst invasive plants. Its dense canopy and rapid spread through underground rhizomes make it a formidable threat to native plants and the animals that depend on them.
There are some redeeming qualities to this invasive plant, however. In addition to goldenrod and asters, Japanese Knotweed is a crucial source of late-season nectar and pollen. At this time of year, when Japanese Knotweed flowers, you can almost locate a stand using just your ears, the buzzing of honey bees gathering the last of their winter food supply from the thousands of tiny flowers is so loud. A wide variety of insects can be found on this member of the Buckwheat family eating leaves, foraging for nectar and pollen, and preying on the former. A recent survey revealed honey bees, bumble bees, ladybug beetles, flies, hornets, yellow jackets, stink bugs and tussock caterpillars, to name just a few.
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Miterwort (Mitella diphylla), also called Bishop’s Cap, is named for the resemblance of its two-peaked fruits to the hats (known as miters) worn by bishops of the Roman Catholic Church. This spring wildflower produces miniature five-pointed snowflake flowers that beg to be examined with a hand lens.
Gnats, small bees and syrphid flies all seek out Miterwort for its nectar. Because its nectaries are located just below the stamens, the flower is pollinated by the mouthparts of the pollinators which brush against the stamens when collecting nectar and the inadvertently-gathered pollen is transported to other Miterworts. Predators such as the Goldenrod Crab Spider (pictured) know that potential meals are plentiful near these delicate flowers.
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With frost just a whisper away, and in some areas not even that, there are still hardy plants, many in the Composite family (goldenrods, asters, thistles, Queen Anne’s Lace, Yarrow), which defy the odds and optimistically send forth blossoms on the off chance that there are still pollinators on the wing. Fortunately for them, bumblebees can and do fly at much cooler temperatures than honeybees and other pollinators. When food is plentiful and outside temperatures fall below 50°F., bumblebees generally stay inside their nest and live off their stores. At times when food is scarce or stores are low, they will forage when the outside temperature is as low as 43°F. (In severe conditions they have even been known to vary their flying height to and from the nest to take advantage of any temperature differences.) Locally, Tri-colored Bumblebees (Bombus ternarius) have a near monopoly on the last vestiges of nectar and pollen (see photo).
Grass of Parnassus, Parnassia glauca, (also known as Bog- Star) was named after Mount Parnassus in central Greece. It is not a type of grass, but rather, belongs to the family Celastraceae and can be found growing in fens, bogs and swamps. The striking green lines on its petals guide flies, bees and other pollinating insects to the flower’s supply of nectar.
The structure of Grass of Parnassus’s flower is not typical. In between its five functioning stamens and five petals there is a whorl of five sterile stamens, each of which is three-pronged. The spherical tip of each prong mimics a glistening droplet of nectar. These stamens do not actually produce any nectar – they are there purely to attract pollinators. The actual nectar is located near the base of these false, or sterile, stamens. Only one of the five true stamens in the flower is active at any one time, with each producing pollen on average once every 24 hours.
Goldenrod is one of the most important flowering plants for honeybees because it is a prolific producer of nectar and pollen late in the year. Blooming in the late summer and fall, this bright yellow-flowered composite provides nectar for the bees to build up stores of honey for winter. (Goldenrod honey is dark amber and strong tasting.) Goldenrod also provides pollen to help stimulate the colony to produce brood late into the fall. The pollen adds considerable amounts of protein, fats, and minerals to the diet of the late-season bees, helping ensure that they will have food throughout the winter.
The month of June can’t go by without a mention of Showy Lady’s Slippers. Just fifty years ago, this orchid could be found over most of the Northeast. Habitat loss and an exploding deer population are considered major factors in Showy Lady’s Slipper’s decline, making it endangered or on the verge of extinction in many areas. Although rare, it is still locally abundant, particularly in fens (peat wetlands that get their water from rainfall and surface water).
As with Pink and Yellow Lady’s Slippers, one of Showy Lady’s Slipper’s three petals is greatly modified into a large inflated pouch called the labellum . (The pouch’s color can vary widely from year to year, depending on the ambient temperature. Cooler conditions appear to produce more intense color.) The petals on either side of the pouch attract pollinators with an alluring odor, but the insects that enter into the pouch are in for a disappointment, as lady’s slippers produce little or no nectar. The structure and positioning of the pistil and stamens are such that they encourage cross-pollination to take place, which is crucial, as lady’s slippers rarely self-pollinate.
Ragged Robin, Lychnis flos-cuculi, is native to Europe and has become so abundant in northern United States that it borders on being considered an invasive plant. Found usually in wet areas such as marshes, fens and wet meadows, this perennial can cover an area as large as an acre. When flowering, Ragged Robin is very noticeable — not only to humans, but also to the many insects that pollinate it. Bees and butterflies, especially, flock to stands of this plant in order to obtain its nectar and white pollen. (If you suck the base of the flower, you will soon detect the sweetness that attracts pollinators.)