Tuesday, July 22, 2014

Wildflowers of 2014 - #182 through #189

On Thursday (17 July 2014) I headed to Mill Pond Park to look for wildflowers.  In about 90 minutes of searching I was able to find eight new species, bring the total for the year to 189 species.  Several of the species were first time finds for me.

Wildflowers of 2014 - #182 Common Evening-primrose (Oenothera biennis)

The first flower of the day was Common Evening-primrose (Oenothera biennis).  The flowers of Evening-primroses open at night to attract moths.  The flowers then close up during the course of the day.  Common Evening-primrose flowers are yellow, have four petals, and measure 1 to 2 inches across.  They grow in spikes at the ends of the plant.

Common Evening-primrose surrounded by White Sweet Clover

Common Evening-primrose plants may be up to six feet tall.  As their scientific name implies they are a biennial - flowering in their second year.  The plant's leaves are oval or oblong-shaped and measure 4 to 8 inches long.

Common Evening-primrose -  a closer view of the flowers and leaves

Common Evening-primrose usually prefers dry sandy soils found along roadsides, shorelines, forest edges, and fields.  It has a very wide species distribution and can be found from the Atlantic to the Pacific coasts with the exception of Idaho, Wyoming, Utah, Colorado, and Arizona.

Wildflowers of 2014 - #183 Spotted Knapweed (Centaurea stoebe)

The next flower is considered a noxious weed or an invasive species by many states.  Spotted Knapweed (Centaurea stoebe) is a native of Europe that was introduced to the Pacific Northwest in the late 1800s.  It is now found in 46 states and seven Canadian provinces/territories.  Spotted Knapweed spreads aggressively by producing large numbers of seeds that remain viable in the soil for several years.  Once established it quickly outcompetes native species.

Spotted Knapweed bloom

Spotted Knapweed plants may grow up to five feet tall.   The purple flowers resemble those of thistles, but the plant can be distinguished from thistles by its complete lack of thorns.  The leaves and stems of Spotted Knapweed are grey-green in color.  The leaves are deeply lobed.

Wildflowers of 2014 - #184 Common Water Horehound (Lycopus americanus)

The third flower of the day is one that I have not found before - Common Water Horehound (Lycopus americanus).  This native member of the Mint family (Lamiaceae) grows in wet soils along shorelines and streams, along the edges of marshes and swamps, and in other areas of low ground.  Also known as American Bugleweed, this species is found across most of North America south of the Canadian Arctic.

Common Water Horehound (Lycopus americanus)

Common Water Horehound may reach heights of heights of up to 36 inches.  It has leaves arranged in opposite pairs.  The leaves are 1 3/4 to 3 inches long and have coarsely toothed margins.  The plant's small white flowers grow in a whorl at the leaf axils.

Common Water Horehound - note whorls of white flowers in leaf axils and coarsely toothed leaves

Wildflowers of 2014 - #185 Self-heal (Prunella vulgaris)

The next flower is another native member of the Mint family.  Self-heal (Prunella vulgaris), which is also known as Heal-all, is found across the Northern Hemisphere in both North America and Eurasia. Unlike the previous species, this species has flowers that grow in a spike above the leaves.  The flowers may be purple, violet-blue, or even white.  Plants grow up to 20 inches tall.

Seld-heal or Heal-all

Wildflowers of 2014 - #186 Northern Water Plantain (Alisma triviale)

Northern Water Plantain (Alisma triviale) is an emergent wetland species.  It grows in shallow water in streams, ponds, lakes, ditches, marshes, etc.  It can be found throughout Michigan.  Overall it has a range that covers most of North America north and west of a line from Virginia to Texas.

Northern Water Plantain - note basal leaves and widely branching flower panicle

Northern Water Plantain plants have a basal cluster of oval shaped leaves on long stalks.  A flower stalk grows up from the central cluster.  This single stalk then branches many times forming a structure called a panicle.  The plants flowers grow on the tips of the many small branches of the panicle.  Although the whole flowering panicle may be three feet (or more) tall, the individual flowers are small, measuring 1/4 - 3/8 inch across. 

Northern Water Plantain - a closer view of an individual flower

The closely related Southern Water Plantain (A. subcordatum) has even smaller flowers that measure only 1/8 - 1/4 inch across.  To distinguish between the two species compare the length of the flowers petals to its sepals.  If the petals are longer than the sepals it is A. triviale, if they are the same length or shorter the plant is A. subcordatum.

Wildflowers of 2014 - #187 Willow-herb (Epilobium ciliatum)

Like Common Water Horehound, Willow-herb (Epilobium ciliatum) is another new species for me.  I found this plant growing in the floodplain area at Mill Pond Park.  This species is typically found in wet soils.  This species can be found across North America with the exception of seven states in the Southeast and the Canadian territory of Nunavut.

Willow-herb (Epilobium ciliatum)

Epilobium species can be difficult to identify to the species level.  I based my identification of this plant on its height (greater than 3 feet), the size of its flower, size of leaves, toothed margins of its leaves, and locations of known populations in Michigan.  However, this species is known to hybridize with Cinnamon Willow-herb (E. coloratum) and the plants in this small colony may very well be hybrids.

Willow-herb - note flower with four notched petals and toothed leaves

Wildflowers of 2014 - #188 Ditch Stonecrop (Penthorum sedoides)

I found the next plant growing several feet away from the Willow-herb.  Ditch Stonecrop (Penthorum sedoides) is another wetland species, growing on the borders of streams and ponds, in marshes, and in other muddy habitats. This plant is found across eastern North America with several small, presumably introduced populations in the Pacific Northwest.

Ditch Stonecrop (Penthorum sedoides)

Ditch Stonecrop typically grows to a height of 1 to 2 feet.  It has narrow oval shaped leaves that are 2-4 inches long.  The leaves are arranged alternately on the stem.  The plant's flowers grow on a raceme - this means that individual flowers all grow on short stalks off an elongated stem with flowers growing from the base of the stem blooming before those at the top.  The racemes may be 1-3 inches long, but individual flowers only measure about 1/4 inch across.  The flowers are cream colored, with red fruit growing after pollination.

Ditch Stonecrop - note small cream-colored flowers (often lacking petals)

Wildflowers of 2014 - #189 Common Burdock (Arctium minus)

The final flower of the day was Common Burdock (Arctium minus).  This introduced species is a common weed of fields, roadsides, pastures, and other disturbed spaces.  Common Burdock (also known as Lesser Burdock) is native to Europe, but can now be found across most of North America with the exception of Alaska and the Canadian Arctic.

A large Common Burdock - note large basal leaves and purple flowers

Common Burdock plants can be identified by their large leaves (up to 2 feet long and 1.5 feet wide), purple flowers, and round burs.  The burs encase the plant's seeds and are used to disperse the seeds.  Anyone who has ever brushed up against one of these plants is familiar with how the hooked burs cling to clothing (or animal fur or feathers) and pull off of the parent plant.  Common Burdock plants may grow from 3 to 6 feet tall.

Common Burdock - a closer view of the flowers and burs

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