Spiny Thistle - Big Spine - Horrid Thistle - Yellow Thistle
Cirsium horridulum Var: megacanthum (Michx)
Syn: Carduus spinosissimus (Walt)
Asteraceae (Composite Subflower) Family


Spiny Thistle is an upright biennial with a taproot. Its preferred habitat is shores, marshes, sandy or peat fields and roadside. Distribution is throughout the Escambia region.

The leaves may be 10 inches or more in length, lance-like in outline, pinnately lobed, no leaf stalk, clasping. The leaf margins and tips are spiny.

The flowers are wide heads made up of tiny five-part tubular discs. Each flower is enclosed in weak-spined bracts. The heads are surrounded by erect, narrow, spiny bract-like leaves. Colors range from white, yellow, purple, red or lavender. Flowers occur in the spring and early summer.

Though found along the edge of salt marshes it is a pasture weed in the Escambia region, where it displays itself in various colors. The plant is sometimes confused with Prairie Thistle (C. plattense), that is also yellow, but its leaves are velvety beneath and grayish above with leaf bracts extending outward like tiny wings.

Fruit is a seed which outer layer is fused to it (achene).

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