[6] Arnoglossum plantagineum is a large herbaceous perennial up to 100 cm (40 inches) tall, spreading weakly using underground rhizomes.

Non-flowering plants have ovate to oval-shaped leaves that are 17 cm wide with long petioles and five to seven nearly parallel veins.

The leaves become smaller as they progress to the top of the stem and the leaf blades are more broadly egg-shaped with more coarse teethed margins and have shorter stalks.

The ripe seeds (cypselae) are dark brown and fusiform or clavate in shape, and 4–5 mm long, and have from 12 to 15-ribs.

[10] In Minnesota the species was relatively common in the southeastern part of the state until recently, when much of its native habitat was converted to farmland, and now is found in isolated remnant colonies along old railroad-right-of-ways.