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Flora Emslandia - Plants in Emsland (northwestern Germany)

Hydrocotyle, water pennywort

Hydrocotyle Linné: The botanical name is made up of gr. hydor (water) and gr. kotyle (navel, small hollow). It was used the first time in 1700 by Joseph Pitton de Tournefort (1656–1708) in his work Institutiones Rei Herbariae and adopted in 1753 by Linnaeus. The English name refers to the shield-shaped leaves of Hydrocotyle vulgaris, corresponding approximately to a penny in size and shape and to its (semi)aquatic lifestyle.

Comprising some 100 species, the genus occurs in the tropical, subtropical and temperate zones of the Americas, Africa and Europe. These are perennial herbs with creeping, prostrate or ascending stems, or annual herbs with erect stems. In most cases, they are marsh plants. The shoots are tender and root at the nodes. Sometimes underground runners are formed. The round, kidney-shaped or heart-shaped leaves may be entire, lobed or notched. The in all species existing petioles show at the base membranous stipules.

The small, mostly hermaphrodite and actinomorphic flowers appear in clusters, whirls, heads or spikes, or solitary in the leaf axils. Sometimes bracts are formed. The 5 sepals are small or missing entirely. There are 5 white, greenish, yellowish or reddish, ovoid, usually pointed petals present..

The 5 stamens are arranged each between the petals. The inferior ovary is composed of 2 carpels and shows 2 styles with simple scars. After self-pollination or pollination by small insects, a spherical or elliptical, flattened, ribbed, usually winged fruit is formed, which containing 2 seeds.

Floral formula:

* K0–5 C5 A5 G(2) inferior

The only water pennywort species that is native to Germany is Hydrocotyle vulgaris. In Lower Saxony and North Rhine-Westphalia also occurs Hydrocotyle ranunculoides, the floating pennywort, which was introduced from North America.

Bedeutung des Artnamens

• vulgaris: lat. vulgaris = common

Interesting notes

• The Brazilian pennywort (Hydrocotyle leucocephala) is considered undemanding aquarium plant.

• The Asiatic pennywort is an ancient Chinese medicinal plant. However, it belongs to the genus Centella, which belongs to the celery family.

• The genus Hydrocotyle was classified for a long time to the Apiaceae (celery family), with which it is closely related.