2018-07-21 / Columnists

Nature Notes

Summer Flowers Are in Full Bloom
By Patricia Martin

A week or so ago I was biking around the east shore of the Island when it struck me that the summer flowers were in full bloom. I think that the warm weather and lack of rain have pushed all our plants along at a faster pace. Along the road the wonderful (and decidedly strong) perfume of the common milkweed (Asclepias syriaca) was enveloping as I passed by and the bright sunny yellow of the lanceleaved coreopsis brightened the margins of the road along with a variety of other blooms.

Common milkweed is a ubiquitous perennial herb which is native to southern Canada and most of U.S. east of the Rocky Mountains. It is generally found in sunny areas on sandy, or at least well-drained, soils. On Mackinac it is found along the shore road, in open areas and along roadsides.common milkweed may also be called butterfly flower, silkweed, silky swallow wort, and virginia silkweed.


Lance-leaved Coreopsis Lance-leaved Coreopsis Overall, common milkweed grows to about two to four feet in height. All parts of this plant produce white latex when broken, which explains its common name.

The flowers are a dusky pink to greenish-purple color, very fragrant, and are arranged in a cluster which appears dome or ball shaped. What appears to be petals are cupshaped structures, each surrounding a single, curved “horn.” The five recurved petals (pointing backward along the flower stalk) are right below this crown. Below the petals are five smaller, greenish sepals.

The stems are stout and hairy and grow from underground rhizomes.

The leaves are thick and about four to six inches long and about a third of the length wide, giving the leaf an oval to ovate to lanceolate shape. The margins of the leaves are smooth (no teeth or undulation) and often the main veins are reddish in color. They have very short petiole and are velvety hairy on the underside. They are arranged oppositely along the stem and sometimes in a whorl.


Common Milkweed Common Milkweed In the late summer to fall this plants produces “seed pods” that are long, pointed, and covered with wart-like bumps. The seeds are tipped with long silken hairs that act as parachutes to distribute the seeds in the wind.

A number of insects eat the leaves of common milkweed, the most famous, of course, is the monarch butterfly larvae which only eat milkweed. Milkweed contains large quantities of glycosides which are toxic to birds so, by eating milkweed, larvae are insured protection from predatory birds as the birds learn quickly not to eat monarch caterpillars or butterflies.

Over the last 10 years the populations of monarchs have rapidly declined and one of several reasons for this is the decline in milkweed in and near fields owing to the spraying of herbicides. Many people, including the Mackinac Island State Park, have planted milkweed to encourage the monarch population. There are 13 different species of milkweed native to Michigan, many of which are showy and are easy to grow.

The common milkweed has been used for a variety of purposes over the years. Attempts were made to exploit the rubber made from the latex, which was not economically feasible. During World War II, the down from the seeds where used to replace the Kapok from Asia that was used to stuff life jackets for buoyancy. The blast, or inner bark fiber, is strong and soft and has been used by native Americans for cordage and textiles. The plant, despite having glycoside, can be eaten, particularly the young shoots, young leaves, flowerbeds, and immature fruits.

The other flower that is blooming in abundance is Lance-leaved coreopsis or tickseed (coreopsis lanceolata). This member of the composite family, or Aster family, if you would, is one that is commonly found in gardens. In the wild the plants are commonly found in dunes, dry woods, and meadows and at Mackinac are usually blooming in July and early August. The plant stands two to three feet tall and the stems are smooth. The stems tend to be quite erect but may be found in a reclining position.

The flower head (which is really a cluster of many flowers) is conspicuously bright yellow, borne singly at the tips of the long stems. There are eight ray (six to ten) flat flowers that are on the outside with three to seven (usually four) lobes at the tip. These surround the darker yellow disk flowers in the center of the flower head. There are two sets of bracts at the base of the flower head. The entire flower head is about one-and-a-half to two-anda half inches in diameter.

The leaves are lance-shaped (hence the name), two to six inches long with no teeth but may have one to two lobes at the base. The leaves are usually found on the lower part of the plant stem. Years ago when I worked at the State Park I used to collect the flowers of this plant for making a wonderful yellow pigment for dyeing wool.

In this column I have frequently written about nonnative plants that are considered invasive as they disrupt the native species or are harmful to the environment, agriculture, or humans. Both of these plant that or humans. Both of these plants that I have featured are now considered invasive species in other parts of the world. Lance-leaved coreopsis was introduced to Japan and China as an ornamental species and was used in greenification projects, particularly along river banks and railways, however, it is now known to out compete native plant life and has, since 2006, been labeled an invasive species by the Invasive Alien Species Act and so the cultivation, transplantation, sale, or purchase of coreopsis is now prohibited and the plant has become the subject of a nationwide destruction campaign being listed as one of Japan’s 100 worst invasive species. Common milkweed, on the other hand, has become an invasive species in Oregon, which is outside its native range, and in parts of Europe. So as the real estate salesmen always say, value is based on “location, location, location.”

Trish Martin is a year-around resident of Mackinac Island, has earned a master’s degree in botany from Central Michigan University, and owns Bogan Lane Inn.

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