Thistle

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Thistle is a generic name given to a group of plants in the family Asteraceae (sunflower family).

Generally, they are characterized as herbaceous plants with showy flowers and spiny leaves like the one in the picture.

The National Park Service lists five different thistles as invasive species that displaces native plants: Musk thistle; Italian thistle; Canada thistle; Bull thistle; Milk thistle.

Their roots can spread up to fifteen feet in diameter and six feet deep, making removal a challenge. Despite their common names, these plants are native to Europe and North Africa.

© 2005-2007 Patricia A. Michaels