Goldthread

On a recent trip to Vermont, we spotted the bright white flowers of Goldthread (Coptis trifolia) dotting the forest floor’s green carpet.  We saw it growing in mossy areas, and often in the company of Canada Mayflower (Maianthemum canadense) and ferns.

Goldthread (Coptis trifolia), Canada Mayflower (Maianthemum canadense) and ferns

Our timing was perfect to see these tiny flowers, since each half inch diameter blossom is typically only in bloom for about a week.  Each flower is perched about six inches (15 cm) from the ground on its own straight stem.

Goldthread (Coptis trifolia) flowers

From a human’s eye view, the showiest parts of the flower are white petal-like sepals.  The primary function of sepals is to protect the other flower parts while the flower is developing, but in some plants, including Goldthread, they are also a showy part of the floral display to help attract pollinators.

From a pollinator’s eye view, additional flower parts come into focus, and offer some surprises.  Working in from the sepals, the unconventional petals make up the next whorl of flower parts. They are much smaller than the sepals, spoon-shaped, with bright yellow, rounded, concave tips.  Not only are these bright yellow petal tips attractive to pollinators because of their color, but also because they produce nectar, an extra enticement for a pollinator’s visit.

Next are the many stamens, the male reproductive parts. Goldthread stamens mature a few at a time, starting from the outside of their cluster.  As the stamens mature they release pollen from the anthers at their tips.  At the very center of the flower are the green pistils (or carpels), the female reproductive parts.  Pollen must be deposited on the stigmas at their tips in order for pollination to occur.

Goldthread (Coptis trifolia) flower. Only some of the stamens have matured.

Goldthread (Coptis trifolia) flowers. (One with a tiny mystery visitor.) All of the stamens are open for business.

Goldthread (Coptis trifolia) flower, When all of the stamens are mature, as they are in this specimen, they make a perfect rounded cluster.

While we watched, a flower fly (Megasyrphus laxus) visited the flowers.  This little fly seemed to be focused on harvesting pollen.  Flies drink nectar, but they also need to eat pollen for its protein.  Everyone needs a balanced diet!

A flower fly (Megasyrphus laxus) hovering over a Goldthread (Coptis trifolia) flower. This group of flies is also called hover flies, or Syrphid flies.

A flower fly (Megasyrphus laxus) eating pollen from a Goldthread (Coptis trifolia) flower. Its proboscis (mouth parts) are directly touching one of the anthers.

If the flowers are pollinated, fruit capsules develop.

Goldthread (Coptis trifolia) fruit capsules

Goldthread leaves are evergreen. In spring dark green leaves from the previous season are visible, and new leaves emerge concurrently with the flowers blooming.

Goldthread (Coptis trifolia). The dark green leaf is from the previous season, the light green leaves have recently emerged.

Goldthread’s scientific name is based on the shape of its leaves, with ‘Coptis’ referring to their deeply cut appearance, and ‘trifolia’ to the three leaflets of each leaf.  The common name Goldthread refers to the plant’s golden colored thread-like underground rhizomes.

Goldthread is a member of the Buttercup (Ranunculaceae) family.  Like some other family members, Goldthread contains berberine, a compound that has anti-fungal, anti-bacterial and anti-tumor properties, among other things.  Plants produce these properties to protect themselves from invaders and consumers.  Although it can be toxic, in the proper doses, Native Americans have found many medicinal uses for this plant.

Goldthread has a northerly distribution. It is native in Alaska, most of Canada except the Northwest and Yukon Territories, the northern tier of the United States from Minnesota east to Maine, and south in the east along the coast as far as North Carolina (except Delaware!).  It can also be found in a few counties in Oregon.  Its preferred habitat is rich, moist woods, and also bogs and swamps.

Goldthread (Coptis trifolia), Canada Mayflower

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Resources

Foster, Steven; Duke, James A.  A Field Guide to Medicinal Plants and Herbs of Eastern and Central North America.  2000.

Hoffmann, David.  Medical Herbalism.  2003.

Mauseth, James D.  Botany An Introduction to Plant Biology.  2014.

Rhoads, Ann Fowler; Block, Timothy A.  The Plants of Pennsylvania.  2007

Stearn, William T. Stearn’s Dictionary of Plant Names.  1996

Minnesota Wildflowers

USDA NRCS Plant Database

Flora of North America

 

The Buzz About Shooting Star

Shooting Star (Dodecatheon meadia) is an herbaceous perennial named for the shape of its flowers and the flowers’ curved stems, which together look a bit like a shooting star with a tail following it through the sky.

Shooting Star (Dodecatheon meadia)

Shooting Star blooms in spring over a period of several weeks. Each flower shoot produces multiple flowers, each flower with its own curved stem (or tail).  The flowers can be white or pink.

Shooting Star (Dodecatheon meadia)

Shooting Star (Dodecatheon meadia)

If the flowers are pollinated, fruit capsules take their place and along with the leaves remain visible for many weeks in the summer.

Shooting Star (Dodecatheon meadia) fruit capsule

Shooting Star requires a partner with special skill to help achieve successful pollination,  an insect with the athletic ability to hang from below the flower and vibrate its wing muscles without moving its wings, in order to shake pollen loose from the flower.  This is called buzz pollination, because the vibration makes a buzzing sound.  Queen Bumble Bees have this ability, and they are the perfect unsuspecting collaborator in Shooting Star’s pollination.

Queen Bumble Bee on Shooting Star (Dodecatheon meadia)

When a female Bumble Bee like the one shown here clings to a Shooting Star flower from below, her abdomen touches the plant’s stigma, the place on the pistil (female reproductive part) where pollen must be deposited if pollination is to take place.  If pollen is present on the bee when she arrives at a flower, it will be brushed from her abdomen onto the flower’s stigma, possibly with some assistance from static electriciy.  As the Bumble Bee clings to the flower she vibrates it, causing a dusting of pollen to be releases onto her abdomen.  She then carries the pollen to the next flower she visits.

Queen Bumble Bee on Shooting Star (Dodecatheon meadia). The flower’s stigma is touching the bee’s abdomen. Notice the dusting of pollen that is beginning to accumulate.

Honey bees don’t have this special skill. Only native bees like Bumble Bees and some others are able to buzz pollinate.  Blueberries, cranberries, tomatoes, eggplants and peppers also require buzz pollination.  If we didn’t have these bees, we wouldn’t have this food!

Shooting Star doesn’t produce nectar, so why would bees keep visiting these flowers?  They don’t do it altruistically, they need some incentive.  Bees visit the flowers for pollen, a food source high in the protein and lipids bees need. After she has visited enough flowers, the Bumble Bee will groom herself, eating some of the pollen and storing the rest on her legs to carry back to her nest to feed her larvae.

Queen Bumble Bee on Shooting Star (Dodecatheon meadia). She has collected pollen on her rear legs to take back to her nest to feed her larvae.

Other small bees may visit the flowers to harvest pollen, but because of the way these smaller bees handle the flowers, the chances are lower that they will encounter the stigma and deposit pollen.

Shooting Star is native in Manitoba in Canada, and much of the eastern half of the United States except the New England states, New Jersey and Delaware.  It is most commonly found in some of the mid-western states.  Shooting Star likes shade to part shade and can be found in open woods.

Resources

Spira, Timothy A.  Wildflowers & Plant Communities of the Southern Appalachian Mountains & Piedmont.  2011.

Rhoads, Ann Fowler; Block, Timothy A.  The Plants of Pennsylvania.  2007

Willmer, Pat.  Pollination and Floral Ecology. 2011

Illinois Wildflowers

USDA Plant Database