• marshmallow, marsh-mallow

From marsh +‎ mallow.

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marsh mallow (plural marsh mallows)

1. 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).
   • 1922, Eleanour Sinclair Rohde, The Old English Herbals, London: Longmans, Green and Co., page 16:

     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.

2. Hibiscus moscheutos (crimsoneyed rosemallow, swamp rosemallow. eastern rosemallow)
3. Malva sylvestris (common mallow)