How to identify Prairie dock (Silphium terebinthinaceum)

How to identify Prairie dock (Silphium terebinthinaceum)

Prairie dock, also known as Smooth Prairie-Dock, Lucy braun's rosinweed, Dock-Rosinweed

Prairie dock boasts a towering stature ranging from 3 to 10 feet (about 91 to 305 cm) high. It displays vibrant yellow sunflower-like blooms, each 2 to 3 inches (approximately 5 to 7.5 cm) in diameter, which make their appearance from July to September. The foliage of prairie dock is distinctive, with rough leaves that are uniquely oriented in a vertical, north-south direction. Beneath the surface, prairie dock is anchored by a formidable taproot that can delve as deep as 14 feet (around 4.2 meters) into the soil.

Lifespan: Perennial

Plant Type: Herb

Leaf Type: Deciduous

Quickly Identify Prairie dock

Vibrant yellow sunflower-like blooms, 2-3 inches (5-7.5 cm) in diameter.

Rough leaves oriented vertically, up to 18 inches (45 cm) long, with serrate margins.

Dock-like leaves near the base, dark green upper surface, light green underside with hairs.

Flattened achenes, tan or pale brown, 0.2-0.4 inches (5-10 mm), easily wind-dispersed.

Green or reddish stem, up to 10 feet (300 cm), leafless with distinctive branching pattern.

Detailed Traits of Prairie dock

Leaf Features

The leaves of prairie dock are large, typically up to 18 inches (45 cm) long and 12 inches (30 cm) wide, oval or heart-shaped, with serrate or dentate margins. They are dock-like and grow near the base of the plant. The upper surface is dark green, while the underside is light green with hairs. The vein pattern is prominent, providing a textured appearance crucial for identifying prairie dock.

Learn About the Leaf Glossary

Flower Features

Prairie dock flowers are 2-3 inches (5-7.5 cm) in diameter, resembling small sunflowers. They feature bright yellow rays and a central disc arranged in loose clusters. Each flower has numerous, thin yellow petals radiating around a prominent, darker yellow central disc. The flowers emit a subtle scent and typically bloom from late summer to early fall, providing a distinctive and vibrant display during the blooming period. Their shape, size, and color are key identifiers of prairie dock.

Learn About the Flower Glossary

Stem Features

The stem of prairie dock is green or reddish, reaching an impressive height of up to 10 feet (300 cm). It is nearly leafless, with a smooth texture and a robust, cylindrical structure. Branching occurs primarily near the top of the stem, forming a distinctive pattern that aids in identification. The stem's thickness decreases towards the apex, supporting the plant's overall stability and height.

Learn About the Stem Glossary

Fruit Features

The fruit of prairie dock is characterized by flattened achenes, which are akin to small, dry, and single-seeded fruits that do not open at maturity. These achenes possess a unique adaptation for dispersal, having a light structure that can be easily carried by the wind. Typically, they exhibit a tan or pale brown hue, blending in with their surroundings. The surface texture is somewhat smooth with a possible slight ridging or winged edges that facilitate wind transport. Each achene measures approximately 0.2 to 0.4 inches (5 to 10 mm), demonstrating a delicate and inconspicuous presence amongst the foliage.

Learn About the Fruit Glossary

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