> Isoetes histrix
The leaves have a dark green colour and are very narrow. They are laid in a helical shape over the stem, which is subterranean, very short and compact.
Photo of Carla Pinto Cruz
In this species of Isoetes, the underground stem is surrounded by dark, shiny, and persistent hooks named phyllopodia.
At the base of the leaves are the sporangia with very small spherical spores inside. These spores are characterized by a tuberculate ornamentation.
They are generally found in the farthest and sandiest external belt of the Mediterranean Temporary Ponds and other temporarily flooded places.
They are distributed in Mediterranean and Western Europe regions.
In Portugal, the known distribution is very restricted.
Although this plant can be seen in other temporarily flooded habitats, it frequently occurs in the priority habitat 3170* of the Directive 92/43/CEE.