Botany Notes Ferns 23rd November 2023

When first becoming interested in wild flowers, it would be the flowering head that was really noticed, soon realising how important the leaves could be and much later probably, that there was also a lot of green foliage around, more in fact than the ‘flowers’, -grasses, sedges, rushes, horsetails and ferns. What follows is a few comments on some of the most common ferns.

One of the most commonly seen ferns locally is Maidenhair Spleenwort Asplenium trichomanes, growing profically on the limestone walls especially on the walls near Linton Falls. Often growing closeby is the Wall Rue Fern A. ruta-muria.

Another  wall-liking fern is the Brittle Bladder Fern Cystopteris fragilis not so common perhaps but often seen.

These three ferns look quite different, the reason being that the fronds are divided differently.

One very common fern Hart’s-Tongue Asplenium scopendrium is not divided at all. It’s fronds are entire and undivided. Each side of the rachis of the Maidenhair is divided into simple segments called pinna and the whole frond pinnate. In the Wall Rue the pinna are divided again into pinnules and known as twice pinnate and in the Brittle Bladder the frond is divided again and known as thrice pinnate.

Three more very common ferns demonstrating again the pinnate nature of ferns are Common Polypody Polypodium vulgare, once pinnate,

Male Fern Dryopteris filix-mas, twice pinnate and Broad Buckler Fern Dryopteris dilitata, thrice pinnate.

In the set featured image at the beginning of the piece the four images in order, reading left to right illustrate the point more clearly.

Two other locally common ferns are Hard Fern Blechnum spicant

once pinnate and Hard Shield Fern Polystichum aculeatum

twice pinnate. The Hard Fern is unusual in having two kinds of fronds,both once pinnate. The outer ones are sterile and the inner more delicate ones fertile.

Hard Shield Fern is similar to Male Fern but has a short bristle at the end of the pinna and it grows downwards from its centre while the Male Fern stands upright its fronds appearing like a shuttlecock.

 

Ferns have a long life cycle which begins with the release of spores from the underside of the pinna. These spores are grouped together in a sporangia which usually have a protective covering an indusium. The way the indusium is arranged on the pinna is an important identification feature.

There are other ferns to be seen locally, some with interesting names, Moonwort Botrychium lunaria and Adder’s Tongue Ophioglossum vulgatum , not easily found, but a final one which is  very commonly seen is Lady Fern Athyrium filix-femina very similarly formed as Male but with  more delicate pinnules.

Of course the most common fern of all is Bracken Pteridium aquilinum, and most likely to be the fern everyone knows.

Most of these ferns can probably still be seen on the walls and in the woods.

Text and photos Christine Bell.