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The flowering stems of Arctium minor may be 1.5
meters tall and the basal and lower leaves may be as large
as 1/2 meter in length and nearly as wide. It is a biennial
species, so during the first year in which a new seedling
becomes established, only the large basal leaves are produced.
During the second year the plant sends up a tall flowering
stem. After flowering and producing seeds, the plant dies.
Arctium minus is a large weed introduced to North
America from Europe and now widely naturalized throughout
the U.S. The "empty" counties on the Wisconsin
distribution map probably indicate a reluctance of people
to collect scientific vouchers of this large weed, rather
than true absence. In Wisconsin it usually begins to flower
in July and continues late into the summer. The fruiting
stems remain upright throughout the next winter. The hooked
tips on the bracts of fruiting heads readily attach
the fruits to the hair (or clothing, etc) of passing animals,
assisting in the dispersal of seeds. The ability of the
fruits to stick tightly to fur or clothes is said to have
been the inspiration for the invention of "velcro".
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