TallThistle

=Tall Thistle= (Cirsium altissum)

(8th period Biology, September 4,2008)

You can tell from the picture that it is a Tall Thistle because of the pink flower and the bracts that surround the flower.

The Tall Thistle sprouts every two years. It can be up to 9 1/2 feet tall. Its flowers are a very distinctive pink. It has a hairy stem and leaves. They usually flower between July and October. They usually appear in non-crop areas.

Leaves
The leaves are alternated along the stem. They don't have many hairs on the top but have lots of pubescent, or covered with white short hairs, beneath. The leaves don't have the stalk that connects to the stem, but are directly attached to the stem. Leaves can be as long and 12 inches long and 4 inches wide.

Stems
Stems stand straight up. The have branches that come off of them and have lots of hairs. Can reach the height of 9 1/2 or taller.

Roots
The Tall Thistle has a taproot. A taproot is a main root that descends down from the radicle and gives off small lateral roots.

Flowers and Fruits
The Tall Thistle gives of an achene fruit. An achene fruit is a small dry hard one-seeded fruit that doesn't open at maturity. The achene is 6 mm long and 2 mm wide. One flower comes off a flowering stem. The flowers are a sort of pinkish purple color. A flower can be 1 1/3 inches in height and width. The flower is surrounded with bracts which are leaflike plant parts.

How to Identify It
The bulb-shaped base below the flower is very helpful when it comes to identify the Tall Thistle as one of the Cirsium species. You can also tell because of the leaves. The Tall Thistle is very difficult to distinguish from the Canada Thistle, Bull Thistle, and the Musk Thistle.(1)

-Mary Martin-

Links
1- www.ppws.vt.edu/scott/weed-id/ciral.htm This is where I got all my information from.