Protologue Description: H. ADPRESSUM, VAR. spongiosum. Quam forma typica robustius erectum 7 cm. altum: caule solitario in parte inferiori incrassato et more Decodonis a cortice crasso spongioso tecto; foliis oblongis quam illi formae typicae latioribus et saturiore viridibus.- Collected by G.G. Kennedy, E.F. Williams and M.L. Fernald, in marshy borders of thickets on the sandy shores of Flax Pond, Bourne Massachusetts, 15 September , 1901. Type in the Gray Herbarium.