Ferns are plants that don’t have flowers. Across medieval Europe, the absence was worrying, and explained as ferns having invisible flowers, and seeds that only appeared on Midsummer night, when they could be collected. The seeds then had the power to make you invisible. In Slavic tradition, the flowers were not invisible, simply very rare and short-lived. Those who caught sight of fern flowers during St John’s Eve (or Ivan Kupala night) would be happy and rich for the rest of their lives.
About 60 species of ferns (Papratnjače) grow wild in Croatia, of which only five are listed in my trusty “Flora of the Adriatic Coast and Islands” book. With that as a starting point, I’ve been seeking out Hvar’s ferns in shady corners, on walls and rock fissures. I’m still working on it, but here’s what I’ve found so far, in latin name order (with the common names in Croatian and English).
Adiantum capillus-veneris (Gospin vlasak, Maidenhair fern) grows around the world in temperate areas from Europe, Asia and America to Australia. Like all ferns, it does need a certain amount of moisture, but here on Hvar it seems happy with shady walls or woodlands, and you may well find them on north-facing dry-stone walls. Around 15-30cm in height, with very delicate fronds subdivided into broad pinnae. The rachis is black and wiry. (Photo courtesy of Wikimedia Commons as I haven’t seen one on Hvar yet to photograph yet)
At this point, let’s run through a basic naming of fern parts. The leaves grow directly out of the rhizome, which is generally underground. The green leafy parts above ground are fronds, each made up of a stipe (up to the leaves) and the blade (leafy section). The leaflets are attached to the rachis, which is simply a continuation of the stipe. Each leaflet is known as a pinna, and a division of that is called a pinnule. On the underside of the fronds, spores are formed in sporangia, arranged in clusters known as sori, which in some ferns are covered by a thin membrane (indusium). The structure of the frond and the level of sub-dividing helps us to identify which fern we’re looking at. A common blade formation is pinnate, in which the pinnae are each sub-divided into smaller versions of the blade itself. It’s a very pleasing fractal pattern, and the Barnsley fern, which looks just like a real fern, was generated by mathematician Michael Barnsley.
Asplenium ceterach (Zlatna paprat, Rustyback) is found in Western and Central Europe, including the Mediterranean region. This fern is quite common on Hvar, growing on sunny walls and slopes, seemingly not in need of great humidity. It can even take full sun and water shortages, happily recovering whenever water becomes available again. That handy ability is due to its high concentration of phenolic compounds which combat dehydration. In folk medicine, it has been used in infusions as a diuretic. The shiny green fronds have a pinnate lamina with rusty-coloured trichomes (hairs) on the lower surface. Hence the name.
Asplenium trichomanes subsp. quadrivalens (Smeđa slezenica, Common maidenhair spleenwort) is a worldwide species, living in a variety of rocky locations, but despite being called “common” it actually appears to be quite rare. Evergreen fronds long and narrow with round pinnae, usually 8-20cm, but can reach 40cm. Stipe and rachis are dark-coloured for the full length. Scales are dark. There are 4-8 sori per pinna.
Athyrium filix-femina (Lady fern) is native throughout the temperate zones of the northern hemisphere. The rather elegant feathery fronds come from a central point, rather than along a rhizome. Fronds are 20-90 cm long, with Sori neatly placed on the underside 1-6 per pinnule, and covered by an indusium.
Cheilanthes acrostica (Mirisav vodjerak, Fragrant lip fern) is found around the Mediterranean (Feb-June) in limestone fissures. Fronds arranged in groups.
Polypodium cambricum (Južna oslad, Southern polybody) is native to southern and western Europe, especially the Mediterranean area, where you can find it on shady rocks. Deciduous spreading fern with fronds up to 60 cm high with between 5-28 pinnae each side. The sori are yellow in winter. Rhizome is often above ground. Polypodium means many feet, as the rhizome bears numerous roots.
And finally, let’s have a look at the sex life of ferns…
The life cycle comes in two parts. First is the sporophyte stage in which the young fern has roots and a leafy part above ground, with sori on the underside of the fronds. When mature, the sporangia burst open, releasing millions of spores which may be carried some distance on the wind. If it lands somewhere suitable, the spore will germinate and grow into a tiny heart-shaped gametophyte plant. On the pointy end of the gametophyte is the antheridia (male part), and near the notch are clusters of archegonia (female parts). The sperm has to make its way from the antherida to the archegonia to fertilize an egg, which requires moisture to help the sperm swim. The resulting zygote will grow into a new fern plant. This is where some amount of moisture is necessary, to help the sperm swim to the egg. For the ferns living in hotter dryer places, such as in the Mediterranean, they need to time their cycle to take advantage of the rainy seasons.
A quick fern quotation from Shakespeare
GADSHILL: “We steal as in a castle, cocksure. We have the receipt of fern seed, we walk invisible.
CHAMBERLAIN: “Nay, by my faith, I think you are more beholding to the night than to fern seed for your walking invisible.”
~ William Shakespeare, from Henry IV (Part I)