Thistles are characteristically seen in pastures and along roadsides with their sharp prickly foliage that run the length of the plant. The small flower on the top of each thistle stem is seen ranging in colors from mauve and white to pinkish purple. Thistles vary in terms of climate preference and grow in moist, wet soils as well as dry, arid climates. Thistle seed is also popular for feeding wild birds and is a favorite of finches.
Pasture thistle, a type of thistle, is a perennial wildflower that grows 1 to 3 feet in height. Its fragrant flowers are white to light magenta in color and grow 2 to 3 inches wide. These striking blooms emerge late spring to summer and prefer dry soils often seen in pastures, hence the name pasture thistle. The foliage of the pasture thistle is long and hairy with shallow, spiny lobes that are green in color.
Swamp thistle is a perennial wildflower that grows in wet woods and swamps. It's rose and purple colored blooms are clustered and attached to hollow stems with sticky bracts. The flowering season begins in the summer and lasts through the fall. The foliage on the swamp thistle is long with deeply cut leaves that are prickly and green in color. Swamp thistle grows between 2 and 8 feet tall.
Yellow thistle is a perennial wildflower that grows between 2 and 5 feet tall. Yellow thistle begins to flower in late spring and lasts through the fall. The 3-inch blooms are yellow with spiny bracts that are white or purple in color. The foliage on the yellow thistle ranges from 2 to 5 inches with bristly leaves that come to a sharp point. When young, the foliage has a woolly texture. Yellow thistle prefers sandy soils and grows in fields, salt marshes, roadsides and savannahs.
Bull thistle is a biennial plant that grows 3 to 6 feet in height. Its purplish pink flower blooms grow up to 2 inches in width with stiff and rigid spines that resemble a shaving brush. The flower emerges in summer and lasts through the fall. The foliage on bull thistle is spiny with deeply lobed leaves that are pale green in color. These wildflowers are often seen growing in pastures and along roadsides.