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Flora Emslandia - Plants in Emsland (northwestern Germany)

Habit, inflorescence and infructescence of the water arum

Plants perennial, herbaceous, rhizome creeping, green, articulated, slightly spongy, about 2 cm thick, up to 60 cm long.

Stem prostrate to ascending, glabrous, unbranched, 10–30 cm long.

Leaves long stalked, terete, sheathing the stems. Lamina simple, heart-shaped, about as long as wide, leathery, bright green, acute or tapered.

Cataphylls lanceolate, up to 10 cm long, acute.

On the scape there is a short, cylindrical spadix with a thick stalk which is thickly and completely covered with small greenish flowers.

The lower flowers are hermaphrodite and possess a pistil with a sessile, spherical scar and usually 6, rarely 9–12 free stamens. Above the hermaphrodite flowers may be present circles of male ones.

The spadix is surrounded by open, roundish to ovate, acute bract, the spathe, which is longer than the spadix. It is green on the outside and inside white as snow. The base of the spathe is decurrent (extends down along the scape).

After pollination by small flies or beetles, some suspect a pollination by snails, formed from the hermaphrodite flowers 3- to 9-seeded berries which are round to oval, red, and tightly crowded. At fruiting time the spathe withers. Plants legally particularly protected, poisonous in all parts!

Occurrence:
Marshy forests, swamps, edges of ponds and small streams. Prefers slightly shaded, slightly warm and wet locations which are poor of nutrients and chalk.

Distribution:
Europe, Asia and North America.