Althaea officinalis aka Marshmallow

Althaea officinalis, or marsh mallow, is a perennial herb. It belongs to the mallow family, Malvaceae. Its native range spans Europe, central Siberia, and western Pakistan. It also grows wild in northwestern Africa. It is native to Britain and Ireland. Its habitats include stream banks, ditches, and marsh edges. It grows near both fresh and brackish water. Plants have escaped gardens in parts of eastern North America.

Marsh mallow forms tall, upright stems that may branch. Missouri Botanical Garden gives a usual height of 4 feet [1.22 metres]. Its usual spread there is 2.5 feet [0.76 metres]. Larger plants reach 6 feet [1.83 metres] tall. They can spread 4 feet [1.22 metres] wide. RHS gives a larger garden range for both dimensions. Its height range is 4.9–8.2 feet [1.5–2.5 metres]. Its spread range is 3.3–4.9 feet [1–1.5 metres]. Soft hairs cover the grey-green leaves and stems. Leaves have toothed edges and often three to five shallow lobes. The plant loses its leaves in winter.

Small flower clusters rise on the tall stems. The blooms have a shallow, saucer-like shape. Their colour ranges from white to pale or lilac pink. Missouri Botanical Garden lists flowering from July through September. Chicago Botanic Garden records blooms into October. The flowers attract butterflies. This plant suits borders, herb beds, and cottage gardens. It also fits rain gardens and wildlife gardens.

Grow marsh mallow in full sun for best results. It also tolerates partial shade. Fertile, moist soil suits it best. It accepts sand, loam, chalk, and clay. It grows in acid, neutral, or alkaline soil. Wet ground is suitable, though RHS favours moist, well-drained soil. Established plants can withstand short dry spells. Sources rate it hardy in USDA zones 3–9 and RHS H6. Care needs are low. Sow seed in midsummer to raise new plants. Cut stems to ground level after flowering. Flea beetles and leaf rust may occur.

Leaves and roots are edible, raw or cooked. Their mucilage can thicken soups and stews. Raw leaves can feel hairy and fibrous. Roots once formed part of honey-based sweets. Modern commercial marshmallows no longer contain the root extract. Leaves and roots also have a history of herbal use. These uses include soothing irritation in the mouth and throat. Roots can supply glue, and stems and roots yield papermaking fibre. PFAF notes anecdotal reports of allergies and lowered blood sugar.