Bull Thistle (Cirsium vulgare)

Bull Thistle (Cirsium vulgare)

The Bull Thistle (Cirsium vulgare) herb/forb in the Aster Family (Asteracceae) and order Asterales. It is uncommon around French Hill Pond but has been found in this area. The photograph on this page was taken to the east of the pond. Note the French Hill Pond island in the background. The genus  name is derived from the Greek words, "kirsion cirsos" which means "thistle (for) swollen vein." In ancient Greece this plant was used to treat swollen veins. The species name, vulgare, is Latin for "common."  This biennial forb can grow to six feet (1.80 meters) tall. The flower head can be as large as two  inches (five centimeters) in diameter. The green, spiny bracts with sharp, yellow tips surround a cluster of purple disk flowers. This plant flowers from June to as late as October. 

Bull Thistle (Cirsium vulgare) Flower

The leaves are pinnately-divided into lance-shaped lobes up to six inches (15 centimeters) long. Each lobe has a sharp tip and numerous spines. The stem and branches are also spiny. Heavy gloves should be used to handle this plant.

Bull Thistle (Cirsium vulgare) Leaves

The fruit is a dry seed attached to a feathery pappus (crown or bristle) that allows the seed to be propagated on the wind. The seed is white to tan. A flowerhead can produce up to 300 seeds.

Bull Thistle in Late Summer

The root system is simple. Propagation is by seed. New plants will germinate before winter, become dormant and grow rapidly the next spring.

Bull Thistles are considered an invasive plant in many states but not in Maine. They tend to get crowded out by other plants in Maine.

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