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Content tagged with "thistle"

Photo of spotted knapweed flower head showing spots on involucral bracts

Spotted Knapweed (Flower)

The black, arrow-shaped spot on each bract gives spotted knapweed its common name.

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Photo of spotted knapweed plant showing foliage and growth habit

Spotted Knapweed (Leaves)

A single spotted knapweed plant can have a single stem or as many as 20 stems. It usually flowers in the second year, producing branched stems. The leaves are alternate, deeply lobed, and pale blue-gray.

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Photo of spotted knapweed rosette, formed in the first year of growth

Spotted Knapweed Rosette

By the end of its first year, a knapweed plant is a small basal rosette. It usually bolts in the second year, producing branched stems.

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Photo of tall thistle plants with flowers

Tall Thistle

Cirsium altissimum
Tall thistle is a native thistle that can grow to be 10 feet tall! To identify it, notice its leaves, which are unlobed (though they may be wavy or have only shallow, broad lobes), are felty-hairy beneath, and have prickles only along the edges.

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Photo of tall thistle plants with flowers

Tall Thistle

Tall thistle is a native thistle that can grow to be 10 feet tall! To identify it, notice its leaves, which are unlobed (though they may be wavy or have only shallow, broad lobes), are felty-hairy beneath, and have prickles only along the edges.

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Photo of cut-leaved teasel showing flowerhead and joined, cuplike leaves.

Teasels

Dipsacus fullonum and Dipsacus laciniatus
“Infestation” is the term for what teasels are doing in Missouri. Learn to identify these thistlelike plants, and help to control the weedy spread of these tough, prickly invaders.

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