It is native to central and eastern North America where it is found primarily in the Midwest and Upper South of the United States.

[5] H. appendiculatum is a biennial herbaceous plant that grows to a height of 30–76 centimetres (1–2.5 ft) with branching, hairy stems.

[5] The inflorescence is a loose cluster, or cyme of pinkish purple or lavender flowers at the ends of the stems and branches rising above the leaves, 5–8 centimetres (2–3 in) long.

[3] This species can be distinguished from Hydrophyllum canadense, which has a similar appearance and broad geographical overlap, by the presence of small appendages in the sinuses of the calyx of H. appendiculatum.

[5] H. appendiculum is native to the United States from Nebraska and Kansas to the west, Mississippi and Alabama to the south, the Canadian border to the north, and New York to the east.