Bird’s nest ferns, in general, are characterised via large, long and simple fronds that are arranged in a rosette manner around the center of the plant. Locally, various Asplenium species and their cultivars make up what we call ‘bird’s nest ferns’ and they can be told apart via various morphological details of their leaves.
One rather common but curious-looking cultivar that is often imported, sold and grown as a houseplant is the bird’s nest fern with leaf edges that are cut into thin and wavy sections. Labelled as Asplenium nidus ‘Fimbriatum’, this cultivar is a much slower-growing bird’s nest fern compared to the ones with entire leaf margins. The fronds of this cultivar appear to be rather stiff and the upper portions do not arch downwards.
One morphological feature of Asplenium nidus is that the mid-rib of its leaves are keeled on the underside. What this means is that if one is to feel run our thumb and index finger between the mid-rib in the leaves of Asplenium nidus, one will be able to find that it protrudes more distinctly from the upperside of the leaves .
However, in the case of this cultivar ‘Fimbriatum’, I noticed its mid-rib protrudes more distinctly from the underside of its leaves and this is contrary to what is to be expected from Asplenium nidus, as shown in the picture above. There is another species of Asplenium, A. australasicum, where its mid-ribs protrude from the underside of its leaves. From this observation, I reckoned, the cultivar ‘Fimbriatum’ is more like one of A. australasicum than A. nidus.
The plant I have now is in its juvenile stage and the features of how its spore sacs are arranged on its leaves can only be seen when the plant has grown larger. In A. nidus, note that the length of its sori are much shorter compared to those seen in A. australasicum. The former’s sori often run up to at most half or slightly more across the length between the mid-rib and the leaf’s edge whereas the latter’s are more extensive where the sori can cover more than the length between the mid-rib and the leaf’s edge.
