Maidenhair Spleenwort

In a wood on a steep Northern slope grow Oaks and Beeches that nearly never see the sun. Hidden between the trees, high above the river Dordogne there are some limestone cliffs. Here grows this little fern.

It is a Maidenhair Spleenwort (Asplenium trichomanes), but which one? In Dordogne there are three subspecies known, and this one is rather atypical.

Generally, Maidenhair Spleenworts grow on stone walls or vertical rocks, like here. They all have fronds with a dark brown  central stem, the rachis, that is pinnate compound, with on both sides small simple green leaves.





Here a Common Maidenhair Spleenwort as can be found in many places: Asplenium trichomanes subsp. quadrivalens. It has rather long fronds tapering towards the end, with symmetrical pinnate leaves that are finely dented.

The subspecies here below grows mainly on vertical limestone rocks, like cliffs or cave entrances.

This Maidenhair Spleenwort  (Asplenium trichomanes subsp. pachyrachis) is much less common, already because the right kind of vertical limestone rock is not everywhere, not even in Perigord. It is tiny and its fronds follow the rock surface as if they are glued to it. The pinnate leaves cover each other like roof tiles.


But this fern? It looks a bit like the subspecies above, but...

It has rather long pinnate leaves lobed like little hands that do not cover each other like roof tiles. And the end leaf is at least twice as big as the others. The fronds are free from the rock, not glued to it, and they heve everywhere the same width instead of tapering. It does not look like a Perigordian subspecies, it looks more like a subspecies that grows exclusively in the Alps. Quite improbable to find that one here...

Moreover, when you look at the underside of a fertile frond as in the centre of the image here below, you see is has not many sores. The sores are the whitish small structures wherein sporangia (here tiny black points) develop. Are there fertile spores in those sporangia? Now way to know without a microscope.






Hybrid plants are sometimes less fertile than pure species. Is it possible this plant is a hybrid, and in case of yes, between which species or subspecies?

Maybe yes. We do not know yet very well the Spleenworts and their subdivisions and how species and subspecies can be distinguished and how they differ. They are tiny plants, often rather inconspicuous and growing in places difficult to get to. Not easy for botanists.