Wednesday, August 17, 2016

Wildflowers of 2016 - #220

On Monday (15 August), I stopped at Island Park to look for wildflowers.  Island Park is located in downtown Mt. Pleasant and is heavily developed.  It would not seem to be a very good place to search for wildflowers.  However, it is surrounded by the Chippewa River and the riverbank has largely been left in a natural state.  I found several species of wildflowers in bloom, but only one was a new one for 2016.

Wildflowers of 2016 - Common Cocklebur (Xanthium strumarium)

Common Cocklebur (Xanthium strumarium) is general considered native to North America, but  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. 

Common Cocklebur growing in the floodplain of the Chippewa River

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 Coccklebur - note the large cordate (heart-shaped) leaves

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 flowers - male (staminate) flowers are the small globes with protruding stamens; bur-like structures are the female (pistillate) flowers

One cool fact about this species is 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.

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