Calla (also known as Water Arum, Bog Arum, Marsh Calla, Wild Calla, or Squaw Claw) is a genus of flowering plants in the family Araceae, containing the single species Calla palustris. It is native to cool temperate regions of the Northern Hemisphere, in central, eastern, and northern Europe (France and Norway eastward), northern Asia, and northern North America (Alaska, Canada, and northeastern contiguous United States).
The genus formerly also included a number of other species, which have now been transferred to the separate genus Zantedeschia. However, these plants from tropical Africa are still often termed "Calla Lilies" but should not be confused with Calla palustris.
Water Arum is a rhizomatous herbaceous perennial with a thick branching rhizome. Leaves are glossy, dark green, and heart-shaped. Flowers are small, yellowish-green, and produced within white spathe. The fruit is a cluster of bright red berries.
Growing Conditions and General Care
Water Arum is found in bogs and marshes as it is a plant of shallows, cold water, and wet soils. It can tolerate up to 2 inches (5 cm) of standing water and grows best in full sun. It grows from submerged creeping rhizomes that are horizontal near the surface of the soil. In summer, the growing shoots can be cut off to encourage branching and pushed into the soil to propagate. These perennials also frequently vegetatively reproduce by producing offsets through their rhizomes.
It can be grown in wet soil and marshy, muddy conditions with still, shallow freshwater. Plants tolerate close to full shade but may become weak-stemmed and lean. In established ponds with a good layer of sediment at the bottom can be left to free float.
The rhizome of the Water Arum grows horizontally, running along the surface of the pond and forming roots at nodes. It may suffer from sunburn during high heat periods but will put on a new growth spurt in the cooler autumn days.
A light mulch is necessary for extremely cold, snowless winters. Water Arum will not survive a dry spell.
It can be propagated by seed or division of the rhizome.
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