Nature Bulletin No. 443-A February 5, 1972
Forest Preserve District of Cook County
George W. Dunne, President
Roland F. Eisenbeis, Supt. of Conservation
The prickly purple-flowered thistle has been the national emblem of
Scotland for hundreds of years. In the 13th century, when that country
was a separate kingdom, it was invaded by Norsemen. According to
legend, when they made a stealthy night attack on the Scottish camp at
a place called Largs, one barefoot Dane stepped on a thistle and his
yell of anguish aroused the Scots who fell upon the miscreants with
claymore, dirk and bludgeon, put them to flight and drove them back
across the North Sea. One of the proudest orders of knighthood, called
the "Order of the Thistle", or "Order of St. Andrew", was established
in 1540 by King James V of Scotland.
Thistles are the armored knights of the vegetable kingdom. Their
leaves, bristling with needle-sharp spines, protect them from grazing
and browsing animals, so that in closely cropped pastures we
commonly see tall thistles standing here and there. A burro or donkey,
however, will nip off the flower heads and chew them with relish. As
boys, we used to do that and spit out the purple juice. They taste good.
Bumblebees and butterflies, which have long tongues, feast on the
nectar at the base of those tubular flowers.
Thistles belong to the largest of all plant families, the composites, and
to the group with blossoms composed entirely of tubular disk flowers.
Their seeds, each with a pappus or tuft of silky hairs like those of the
dandelion, are widely spread by winds. Thistledown is a symbol for
fineness and lightness. One bird, the gay little goldfinch, does not
build its nest until midsummer when thistles have ripened and this
down can be used for lining. Of more than 200 kinds distributed over
the northern hemisphere, there are about 75 in the United States
including some 50 in the west and southwest, two found only in
swamps, and three with yellow flowers. A number of prickly plants,
such as sow thistle and the Russian thistle (a tumbleweed), are not
thistles at all.
The Bull or Spear Thistle, introduced from Europe, has become
naturalized throughout most of the U. S. and very common. It does not
bloom the first year and flat green rosettes of its leaves may be seen on
the ground in winter. The second year it sends up a stout stalk from 3
to 5 feet tall. Singly, at the top of the stalk and at the ends of its leafy
branches, it bears large purple blossoms.
The Tall Thistle, a native which often attains a height of 10 feet, has
leaves which are woolly-white underneath and usually without lobes.
Another handsome native species, the Field or Silver Thistle, grows
quite tall but its leaves, also woolly-white underneath, are always
deeply cut (lobed). The Pasture or Fragrant Thistle, from 1 to 3 feet
tall, usually has only one broad terminal head of fragrant purple
The Canada Thistle, so-called because it was introduced into Canada
from England, is the most noxious weed in our northern states.
Seldom more than 3 feet tall, with many branches and deeply cut, very
prickly, crinkled leaves, it bears numerous lavender, pink or whitish
flowers. It is also called the Creeping Thistle because it spreads rapidly
by long rootstocks, as well as by windborne seeds, and forms large
patches that crowd out grasses, hay, and grain crops. In many states
there are severe penalties for letting it ripen or for selling seeds which
include seeds of this thistle.
Most weeds have some virtue. This outlaw has none.
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Update: June 2012