Hedeoma hispida Pursh. (rough pennyroyal)
The leaves were used as a cold remedy and to flavor other medicines.
Hepatica americana Ker. (hepatica, waterleaf)
One root to one quart of water was mixed and then drank to stop convulsions, mainly for children.
Heracleum lanatum Michx. (cow parsnip)
The root could either be mixed with water and gargled or dried and chewed to relieve an ulcerated sore throat. The root was boiled and used as a poultice on boils, or the root and flowers could be pounded together and used as a poultice on boils.
Heuchera spp. (alum root)
The root was used for many things. It was mixed with sumac Rhus glabra L. blossoms in water and then used to moisten something soft and rub on gums of teething babies, or just for sore mouths. Alum root was also dried and chewed with only the juice being swallowed for relief of pains in the stomach. The root was mixed with water and rubbed on eye where sore.
Hicoria alba L. (hickory)
Small, fresh shoots were put on hot stones and the fumes inhaled to reduce convulsions.
Hordeum jubatum L. (squirrel tail)
The root was dried and pounded, and put in a cloth and moistened and then put on eye for sty or inflammation of eye lid.
Humulus lupulus L. (hops)
The fruits were steeped in water and drunk to reduce fevers and intestinal pains. Root chewed and applied to wounds.