Friday, January 8, 2010

The Hidden Secrets of Ferns

Fern spores are produced in vast numbers on the understide of fern fronds during the summer months. For details of how they are catapaulted into the airstream, take a look at

Each spore is less than a hundredth of a millimetre in diameter and can be carried vast distances on air currents. Ferns are often the first plants to colonise bare volcanic lava flows, carried there as spores on the wind.

All they need for germination is water and mineral salts. They swell, the brown spore case splits open and a hair-like rhizoid emerges, that anchors the spore to its substrate. Then a green photosynthetic cell emerges from the spore.

The photosynthetic cell divides longitudinally, forming the beginnings of a short chain of cells. The green blobs in the cells are chloroplasts.

The chain of cells continues to elongate until it reaches 6-7 cells long, dividing longitudinally and producing more rhizoids to anchor itself more firmly. At this stage the remains of the brown spore coat is still visible. During this stage of development the plant must be constantly wet - even a short period of drought will be fatal. I sowed these spores in September, so they've taken about four months to reach this stage, where they appear to the naked eye as a green film covering wet soil.

This is the next crucial stage in development and is about a millimetre long. The tip cell of the thread now begins to divide laterally and longitudinally, forming a flat plate of cells ....

... here you can see this two-dimensional tip division at higher magnification. The flat plate of cells that develops from this is known as the prothallus, and this is where fern sexual reproduction takes place..

These are two fully developed prothalli, each about 5mm. in diameter and only one cell thick. They are incredibly delicate and must remain permanently wet to survive. At this stage they are about six months old and male and female reproductive cells form on their surface.

These are the male antherozoids, enclosed in a structure called the antheridium. When this bursts the antherozoids are released in swarms and swim, propelled by lashing flagellae, like tiny spinning tops in the surface film of water, in search of a female egg cell inside a long-necked structure called an archegonium, which you can see here. After a successful fertilisation an embryo deveops which ultimately grows into a ....... miniature fern plant. In the early stages, as seen here, it's still attached to the prothallus formed by the germinated spore but that soon withers away and the new fern grows by producing a series of ever-larger fronds. It usually takes about a year after sowing to reach this stage.

Provided you have the required patience, ferns are not difficult to grow from spores. For detailed instructions, visit
For more on the fascinating world of ferns, visit


  1. Fascinating detailed description. Some plants have such complex lives.
    I had a pot of insectivorous plants which died off last winter but the surface was always damp and covered in a green 'slime'. Now it has turned into a pot of ferns. Always exciting when something grows from what appears to be nothing.

  2. We tried to grow some ferns from spores, but they didn't germinate and the pot got mould (I say we, I mean my other half) :( We're not very good at growing things.

    P.S. Sooo very much in agreement with what you said to Dr Gatehouse today about complex and incomprehensibly specialist seminar titles/language in science, Dr G.

  3. Hi Louise, that's often a problem, especially if the spores are sown on a soil medium of any kind. Traditionally gardeners used to sow the spores on the surface of pieces of broken clay flowerpot that had been boiled in water to sterilise them, then kept in a humid container covered with glass.The pores in the clay retain the right amount of water. I've found that sowing the spores on pieces of dead wood that have been boiled works well - the pores in the water retain moisture and if the wood is kept in a lunchbox with wet paper towel on the bottom the spores germinate and grow well.

  4. Hi John, I've had ferns come up in pots of insectiuvorous plants too. I suppose it just goes to show that the spores are everywhere - all they need is somewhere damp to germinate............

  5. Hi Phil,

    My name is Hafiz from Singapore.

    I was looking for photos of spores germinating when I chanced upon your blog.

    I am very impressed with the photos and I was wondering if you could provide me with the originals for these photos of spores germinating.

    These photos will be used for an educational book which I will be publishing soon (mid year 2010) entitled "A Guide to Common Epiphytes and Mistletoes of Singapore".

    I will of course be crediting all photos to you. You can further contact me at my email:

    Thanks again and hope to hear from you soon.

    Nor Hafiz Hassan


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