Spores on ferns

Have you found strange brown formations or spots on your fern? Don't worry just yet! It's most likely just that your fern is now mature and has started to grow sporangia on it's fertile fronds.

Sporangia on Microsorum sp.

What are spores

Ferns are a group of non-flowering plants that reproduce through the production of spores. Unlike flowering plants, which produce seeds, mature ferns produce small, lightweight structures called spores that are dispersed by the wind. When these germinate they grow into small heart-shaped plants known as prothalli .

Some ferns produce different types of leaves -sterile and fertile leaves. A good example is the Staghorn fern, Platycerium sp., which has basal fronds (also called back plates) which are the fronds that covers the roots, and foliar fronds, which grow up from the plant and eventually produces spores.

- So if you find strange-looking brown formations on the underside of your ferns leaves, there's no need to worry.

Sporangia on Asplenium sp. Birds nest fern.

Grow ferns from the spores

It's not the easiest task to successfully grow ferns from the spores they produce. They need excellent conditions and you need to collect ripe spores. If you want to give it a try, here's our step by step guide on how to germinate and grow ferns from spores:

1. Harvest the spores when they are ripe. The spores are tiny, almost like dust. You can harvest them by carefully scraping the sporangia and collecting the spores on a tray or on a piece of paper. Or you can cut off one of the mature leaves and place it on top of a tray or piece of paper. When they spores are ripe they will fall onto the underlaying material. You'll find a Brown, Black or Yellow powder.

2. Set up a shallow tray or pot with a good quality soil made out of mostly peat and vermiculite. - To increase the chances of a successful germination you can sterilize the soil with heat first. This will prevent fungi, bacteria and fungus gnats to disturb the germination.

3. Sprinkle the spores evenly on top of the soil and mist the surface so the soil is evenly moist.

4. Cover the container to create a mini greenhouse. You can place the container in a clear plastic bag, cover the container with plastic wrap or place a dome out of glass or a cut plastic bottle on top of the container.

5. Place the container in a warm and bright spot that's protected from too much direct sun and keep an eye on the growth. You might need to water them more, or vent out excess humidity.

- It will take between a couple of weeks to a couple of months before the spores germinate. When the germination has begun, the surface will be covered with a green moss-like growth. You'll need to wait until the prothalli are formed and well developed before you can start to transplant the ferns into their own individual pots.

Baby ferns grown at a commersial nursery

Want to know more about the life cycle?

Ferns have an unique life cycle that involves two distinct stages: the sporophyte stage , in which the plant produces spores, and the gametophyte stage , in which the spores germinate and give rise to the gametes, or reproductive cells, that will eventually form a new fern plant.

The process of spore production begins with the formation of sporangia, which are small, specialized structures on the undersides of fern leaves. Inside each sporangium, cells undergo meiosis, a type of cell division that results in the formation of haploid cells, or cells with half the number of chromosomes as the parent cell. These haploid cells then differentiate into spores.

Once the spores are formed, they are released from the sporangia and dispersed by the wind. When a spore lands in a suitable environment, it germinates and gives rise to a small, heart-shaped structure called a prothallus. On the prothallus, cells differentiate into gametes, or reproductive cells. These gametes then fuse to form a new fern plant.

Sporangia on Platycerium sp. Staghorn fern.