Wildflowers of 2014 - #218 through #224

The wildflower season just keep rolling on.  The following seven species were photographed at Mill Pond Park on Tuesday 26 August 2014.  I have been unable to finish writing about them until now.

Wildflowers of 2014 - #218 Nodding Smartweed (Persicaria lapathifolia)

The first species of the day is a common weed in both North America and Europe - Nodding Smartweed (Persicaria lapathifolia).  This plant is considered native to North America, but some populations are probably introduced from Europe.  It is found across the continental United States (no Alaska or Hawaii) and the lower tier of Canadian provinces/territories.  It is not common in the Southeast and most populations there are probably introduced.  The plant is typically found in wet soils.

Nodding Smartweed on a sandbar along the Chippewa River

There are fourteen Persicaria species that have been found in Michigan.  Nodding Smartweed is easy to identify by its flower head.  It is the only species that has a densely packed raceme (spike) of flowers that nod or droop downward.  The majority of other Smartweed species have erect flower racemes.  The flowerhead can be 2 to 8 inches long, but the individual flower are only about 1/8 inchlong.  The flowers have 5 tepals (petals) that rarely open completely and are white, green, or pink.

Nodding Smartweed - note the drooping or nodding raceme of small flowers

Nodding Smartweed plants can be up to 4 feet tall.  The leaves of the plant are large (2 inches wide and up to 8 inches long), lance-shaped, and are arranged alternately on the plant's stems.  The petiole (stalk) of the leaf has a sheathe that wraps around the plant's stem.

Nodding Smartweed - note alternate leaves with sheathed petiole (stalk) that wraps around the main stem

Nodding Smartweed is known by a variety of names including Willow-weed, Pale Smartweed, and Curly-top Knotweed.  Smartweeds used to be lumped with Knotweeds (Polygonum), and this plant used to have the scientific name of Polygonum lapathifolium.


Wildflowers of 2014 - #219 Common Cocklebur (Xanthium strumarium)

The next flower belongs to another common weed species - Common Cocklebur (Xanthium strumarium).  This species is general considered native to North America, but like Nodding Smartweed, many populations are probably introduced.   It can be found in 49 of the 50 states (not Alaska) and in the southern parts of Canada.  It grows in a variety of habitats from floodplains, to sand dunes, to farm fields.  The plants that I photographed were growing on a sand bar in the Chippewa River.

Common Cocklebur - note large leaves and small bur-like flowers and seed pods

Common Cocklebur plants grow 2 to 4 feet tall.  They have large alternate leaves which are up to 8 inches long and 6 inches wide.  The leaves are either heart-shaped (cordate) or triangular (deltoid) with toothed margins.  The upper surface of the leaves has a rough texture like sandpaper.  The leaves have long petioles (stalks) that may be as long as the leaves.

Common Cocklebur flowers - male (staminate) flowers are the small globes; bur-like structures are the female (pistillate) flowers

The flowers of Common Cocklebur are much smaller than the leaves.  Each plant has both male and female flowers.  The compound male flowers are whitish-green and measure only 1/4 inch across.  The female flowers are up to 1 1/4 inches long, arranged in pairs, and are green colored.  The base of each female flower is a bur-like bract that will eventually contain the plant's seeds.

Common Cocklebur - a closer view of the staminate and pistillate flowers

One thing that is exciting to me about this flower is the fact that its scientific name starts with an "X".  This is important for anyone that wants to do a nature alphabet.  Species that have names that start with the letter X are in short supply.

Wildflowers of 2014 - #220 Tall Blue Lettuce (Lactuca biennis)

The third species of the day was Tall Blue Lettuce (Lactuca biennis).  This native species typically grows in moist soils in woodlands, floodplains, and along the edges of swamps and other wetlands; it is also less commonly found in drier soils in fields, roadsides, etc..  It has been recorded in 35 states and 10 Canadian provinces/territories.

Tall Blue Lettuce (Lactuca biennis) growing in a floodplain forest

Tall Blue Lettuce plants live up to their name.  They can grow to heights of up to 7 feet and they have blue (sometimes white) flowers.  The flowers are 3/8 to 3/4 inch across.  They grow in a panicle (branched cluster) with between 15 and 34 flowers on each plant.  The plant's leaves are arranged alternately along the stem and are either deeply lobed or toothed.  As the plant's scientific name suggests, Wild Blue Lettuce is a biennial, meaning it lives for two years.

Tall Blue Lettuce flower panicle

Tall Blue Lettuce - a closer view of the small individual flowers

Tall Blue Lettuce - a closer view of the lobed leaves

Tall Blue Lettuce is one of six Lettuce (Lactuca) species that has been recorded in Michigan, but only two of the species have blue flowers; the remaining four species have yellow flowers.  The other blue-flowered species, Woodland Lettuce (L. floridana) has only been recorded in a few counties in southeastern Michigan.


Wildflowers of 2014 - #221 Turtlehead (Chelone glabra)

Sometimes when I go out searching for wildflowers I do it with specific species in mind.  There are some species that I know I can reliably find in a specific place at a specific time.  On this trip, there were four plants that I was expecting/hoping to find.  The first of these species was Turtlehead (Chelone glabra).  This wetland species can be found in both sun and shade conditions throughout Michigan and the eastern half of North America.  Three other, less common, Turtlehead species can also be found in eastern North America.

Turtlehead (Chelone glabra)

Turtlehead - a closer view of its namesake flowers

For more information on this species, please see this species profile from August 2013.


Wildflowers of 2014 - #222 Panicled Aster (Symphyotrichum lanceolatum)

Asters.  I don't know of any other single word that can cause more frustration to the amateur botanist.

A few species are easy, but there are many Aster species that are very similar and can be easily confused.  One species that I find in Mt. Pleasant every single year is the Panicled Aster (Symphyotrichum lanceolatum).  Every year I have to dig through my books and scour the internet to confirm my identification of this plant.

Panicled Aster - the wild appearance of this plant causes many to view it as a weed

Panicled Aster is one of many twenty-nine white- or blue-flowered native Aster species that can be found in Michigan.  These species used to all be lumped under the genus Aster - Panicled Aster was formerly Aster lanceolatus.  In recent years, the species have been divided into six genera, with the majority (including Panicled Aster) being lumped into the genus Sympyotrichum.  What makes Aster identification even more confusing is the fact that many species can hybridize.

Panicled Aster does have some characteristics that can be used to differentiate it from other Aster species.  It has narrow oval, elliptical, or linear leaves.  The leaves may be 3 to 6 inches long.  The leaves taper to a point at both ends.

Panicled Aster - a closer view of the flowers and stem leaves

The plant's flowers are arranged in a panicle (as its name suggests) at the top of the plant central stem.  This panicle (branched cluster) can be up to 8 inches long and 4 inches wide.  Smaller panicles often grow from leaf axils and from smaller stems that branch off of the plant's main stem.  Its flowers are 3/4 to 1 inch across, with a yellow disc surrounded by 20 to 40 blue, purple, or white rays.

Panicled Aster - note the branching structure of the flower panicle

Another factor that can help distinguish Panicled Aster from other similar species is its habitat preference.  It is mostly found in wet habitats such as floodplains, wets woods, and the borders of swamps.  Panicled Aster is found across the Lower Forty-eight states and much of Canada.  From county records on the USDA Plants database it appears to be most common in the Great Lakes and Northeast.

Wildflowers of 2014 - #223 Big-leaved Aster (Eurybia macrophylla)

The next flower of the day was also an Aster - Big-leaved Aster (Eurybia macrophylla).  This species, also called Large-leaved Aster, was formerly known as Aster macrophyllus.  This species is found primarily in the states and provinces surrounding the Great Lakes and in the Northeast.  Populations of it can be found as far south as Georgia and South Carolina (in the Appalachians) and as far west as Manitoba, Minnesota, Iowa, and Missouri.  It mainly grows in mesic (not too wet or dry) soils in upland forest habitats.  The plant spreads both by seeds from underground rhizomes.  It often forms dense colonies.

A colony of Big-leaved Aster (Eurybia macrophylla)

Big-leaved Aster is one of the easiest asters to identify.  It has big leaves (1.5 to 12 inches long).  The leaves are heart, oval, or elliptical-shaped.  The plants have both basal and stem leaves.  The stem leaves are arranged alternately.

Big-leaved Aster - note the large basal leaves and smaller stem leaves

Each plant typically has a single flowering stalk that branches into a flat-topped panicle (called a corymb) that measures from 3 to 8 inches across.  Each individual flower measures 1/2 to 1 inch across.  It consists of a yellow disc surrounded by 9 to 20 rays (petals).  The rays are pale blue, lavender, or white.

Big-leaved Aster - a closer view of the flat-topped flower panicle

Wildflowers of 2014 - #224 Zigzag Goldenrod (Solidago flexicaulis)

The final species of the day was another one that I was specifically seeking - Zigzag Goldenrod (Solidago flexicaulis).  This is one of several goldenrod species that grows in wooded areas instead of open habitats.  It can be identified by its wide leaves and flowers that grow from the leaf axils of its zigzagging stem.  For more information on Zigzag Goldenrod please look at this species profile that I wrote in January 2014.

A colony of Zigzag Goldenrod (Solidago flexicaulis)

Zigzag Goldenrod - note how flowers grow from leaf axils and how the stem zigzags at each axil