marsh mallow noun3 •A European species of plant in the mallow family, Althaea officinalis, historically used medicinally and the source of what became the modern marshmallow confection (which no longer contains the plant).Amongst the herbs to be administered when the charm was sung over him were a yew-berry, lupin, helenium, marsh mallow, dock elder, wormwood and strawberry leaves. — 1922 •Hibiscus moscheutos (crimsoneyed rosemallow, swamp rosemallow. eastern rosemallow) •Malva sylvestris (common mallow) formsmarsh mallows · marsh-mallows