Purple Thistle


Purple Thistle
When spines and beauty
Create a receptacle
The bees dance and dine

Dorothy Rodwell


This is such a nasty plant that the Purple Thistle, Cirsium horridulum, is also known as the terrible thistle. Actually, all thistles can be nasty with their sharp spines.  The horrodulum, what a name, grows from a deep tap root.  An erect and stout herbaceous and hairy mainstem grows from the center of a basal rosette to height  of 6 feet.  Basal leaves vary between 8 and 24 inches.  Leaves are alternate on the main stem and become shorter progressing up the main stem.  Leaves are linear to elliptic in shape , very thorny and deeply lobed.  Branching occurs in the upper most portion of the plant.

At the tips of the branches flowerheads are in bloom or waiting to open. Horridulum is a member of the Aster family.  Like all Asters, there is a cup like receptacle called an invulocre (in-vuh-loo-ker)  that is composed of spiny bracts. The invulocre holds around 50 reddish disk florets each about an inch in length.  The bloom is 2  to 3 inches wide. The inflorescence or flower arrangement  for horridulum and all Asters is called a capitulum.

Horridulum is found in sandy soils in almost every county in the State.  In the picture there are a couple of bumblebees of the species Bombus  wading in the bloom looking for nectar.  This picture was taken in the Everglades Shark Valley. Remember, this is a nasty plant armed with thorns and bumblebees.