Thistle

May 31, 2022

When I approached the small overflow dam on Saturday there were four women already fishing the area.  I noted they spread further along the bank when they saw me, a clear fisherperson way to claim a wider area as “where I am fishing”.  After discovering the green heron feeding on frogs at the riverbank, I decided to walk around the small park to see if there was another place to fish.  I had not brought my fly rod, or I would have probably stopped at several places.  Instead, I kept walking.  That was when a glint of purple caught my eye across the stream.  I crossed a bridge that allowed access to the disc golf course and checked out the flower.  It was a thistle plant lying just off the mowed area of the bank.

When I looked online, I found the musk thistle (Carduus nutans), or nodding thistle, is a biennial plant in the daisy and sunflower family Asteraceae that is native to regions of Europe and Asia.  The thistle usually requires two years to complete a reproductive cycle.  Seedlings emerge any time from spring to late summer and develop a rosette.  The plants overwinter in the rosette stage, sending up a multi-branched flowering stem in mid spring of their second year.  Mature plants reach 3.3 to 4.9 feet (1 to1.5 m) in height and have sharp spiny stems.  The dark green leaves grow to 12 to 24 inches (30 to 60 cm) long, and are coarsely bipinnately lobed, with a smooth, waxy surface and sharp yellow-brown to whitish spines at the tips of the lobes.  The reddish-purple flowers are 1 ¼ to 2 ½ inches (3 to 5 cm) in diameter and commonly droop to a 90-to-120-degree angle from the stem when mature, giving the alternate name “nodding thistle”.  The plant is declared a noxious weed in many US states, Canadian provinces, South Africa, New Zealand, and Australia.  A single flower head may produce 1,200 seeds and a single plant up to 120,000 seeds, which are wind dispersed.  The seeds may remain viable in the soil for over ten years, making it a difficult plant to control

The musk thistle was accidentally introduced into eastern North America in the early 19th century and has been an invasive species since.  The thistle is common and thrives in disturbed and agricultural settings, and typically grows in meadows and grasslands, in heavily grazed land in areas such as pastures, and on open disturbed soil such as roadsides and building sites.  Musk thistle is not a serious weed problem in crops requiring a spring seedbed preparation as tilling eradicates the rosettes established during the preceding summer or fall.  The plant can be a problem in fall-planted grains, alfalfa, or clover if the conditions are favorable for seedling establishment and winter survival.  The economic impact of musk thistle is greatest in pastures and rangeland.  Moderate infestations of musk thistle reduce pasture yields an average of 23 percent.  Livestock usually won’t graze infested areas but occasionally feed on the flower heads.

THOUGHTS:  The words “milkweed” and “milk thistle” are often used interchangeably by those who do not study plants, but they are two very different plants.  Milkweed usually grows to about 2 feet tall with large, bright clusters of flowers on the tops of its stems.  The milk thistle is stout and ridged and can grow to over 6 feet tall.  The top of a milk thistle is crowned with a large purple flower head that is surrounded by ridged sharp bracts.  The bright flowers of milkweed attract a plethora of fauna, whereas milk thistle is an invasive weed that takes over poorly tended fields and roadsides and has become a nuisance in areas of North America.  It seems the value of either species depends on the beholder.  As they say, “One person’s weed is another’s flower.”  The same could be said of humans.  Value seems to come from “worth to me,” and ignores the innate value of all.  Chose to act for all.  Change is coming and it starts with you.