A spot in my garden is being colonised by baby ferns.
The toppling of a gum tree last year created bare ground. After a few months, this has now been smothered by little ferns, the biggest only a few cm long.
Baby ferns. Photo by Leon Perrie. © Leon Perrie, Wellington.
Baby ferns are difficult to identify, but I suspect these are water fern (Histiopteris incisa) and ring fern (Paesia scaberula).
Each baby fern has arisen from a different spore, so many spores have fallen on this spot. Yet, there are no adults of these species within at least 100m, and perhaps even a kilometre or so. Clearly there are a lot of fern spores blowing in the wind!
Ferns, like all terrestrial plants, have a two part life-cycle. This is more obvious in ferns because both parts are free-living.
The typical fern plant produces spores, and releases them into the wind. If the spores happen to land in a suitable spot, they germinate to produce a gametophyte.
Fern gametophyte, smaller than a fingernail. Photo by Leon Perrie. © Leon Perrie, Wellington.
The gametophyte produces eggs, which are held internally, and sperm, which disperse through any free water. Fertilisation produces a sporophyte – the typical fern plant.
Young fern sporophyte growing from the fertilised egg of a gametophyte. Photo by Leon Perrie. © Leon Perrie, Wellington.