FLORA OF ICELAND elements: Hydrocotyle vulgaris, Marsh Pennywort, Vatnsnafli

Hydrocotyle vulgaris; The Marsh Pennywort is a rare species on Iceland. It grows only on thermal soils in a few localities in the south-western region of Iceland. The Marsh Pennywort is - as the name suggests - a plant of very wet soils. It can grow under water for a long time during the vegetation period. It is a peculiar plant for more than one reason. The leaves are special in that the leaf stalks are not connected to the base of the leaves but more or less on the middle of the leaf it self. The botanical expression for this trait is "peltate" leaf form. There is no other plant of the indigenous flora of Iceland that has this trait. Another peculiarity is the taxonomic position. It has always been thought that it is an odd member if the carrot family (Apiaceae=Umbelliferae). Odd, because the flower-arrangement is very different from the classic umbels of the carrot family members. The inflorescence is a small, inconspicuous, compact cluster of flowers in the leaf/stem axils. With some imagination one could envisage an umbel, which is why it was placed in this family. However, recent genetic research shows it is more closely related to Ivy, which is why it is now regarded as a member of the Ivy family (Araliaceae). In many plant guides though, they are still regarded as a member of the carrot family. The Icelandic name of this species is Vatnsnafli.