FLORA OF ICELAND elements: Potamogeton alpinus, Red Pondweed

Potamogeton alpinus; the Red Pondweed is a common pondweed on Iceland. This plant grows submerged in ponds and lakes. On Iceland there are a few more Potageton species growing in ponds, lakes, waterways. They can be differentiated by their leaf-shapes. One has to take into account that submerged leaves and surface leaves can differ. The following table describes the leaf shapes of Icelandic Potamogeton species and closely related species of the pondweed family:

Species name
Submerged leaf-shape
Floating leaf-shape
P. gramineus
sessile, sharply pointed top rather narrow
Broader with long leaf stalks. Also pointed leaf apexes
In ponds and lakes all around Iceland
P alpinus
leaves tapering to the base with obtuse apex's
usually absent,
if present similar to P. gramineus
P. natans
rather broad elliptic shaped. Also pointed leaf apexes
Rather rare
P. perfoliatus
Sessile short/broad leaves
Rather rare: prefers relative warmer conditons
P.  praelongus
Long sessile leaves. Not tapering to the base, almost clasping stems
Rather rare
P. berchtoldii
Linear leaves
Not uncommon
Stuckenia filiformis
Thread-shaped leaves
Differs from Potamogeton species in having a serie of flower bundles along the flowering stems.
Common, also in interior highland ponds
Zanichellia palustris
short gras-like thread-shaped leaves
Inflorescences in leaf-axils composed of just one male eand female flower.
Ruppia maritima
brackish and saline conditions. Individual flowers long-stalked. These stalks spirally coil at fruiting stage.

Alas I do not have pictures yest of other Potamogetonaceae (pondweed family) members.

Potamogeton_alpinus / red pondweed is a member of the pondweed family (Potamogetonaceae). The Icelandic name of the Alternate Water-milfoil is Fjallnykra.

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A brief introduction to Iceland plants
Text & Photographs by Dick Vuijk - unless stated otherwise

a stem with leaves laid bare on a rock
Reload first photo of plants submerged in water

a stem with leaves laid bare on a rock

Reload first photo of plants submerged in water
 Press on photo for full size

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