While browsing through a newly published article on the survey of plants at a forested area at Dover from the online Nature of Singapore journal in April 2013, a fern with the name Taenitis interrupta caught my attention. According to the publication, the fern is rather common in Singapore. An Internet search revealed a few pictures of this fern but they look rather similar to another common fern Taenitis blechnoides. I started to wonder whether these 2 ferns are indeed the same species or are they 2 different species.
The Ferns of Thailand, Laos and Cambodia website described Taenitis interrupta as having sori (spore-containing bodies) usually located near the margin than the midrib of the fronds (leaves) and the sori are often interrupted. On 28 April 2013, while I examining 2 pictures of a forest cockroach (Pseudophoraspis nebulosa) resting on a fern, it occurred to me that the sori of this fern were near the margin of the fronds. I had originally thought that this fern was Taenitis blechnoides. The finding got me quite excited since this might be the Taenitis interrupta fern mentioned in the publication.
Almost immediately, I went to the park where the fern was located to re-examine the live specimen and took a series of pictures of the suspect. In addition, I also took some pictures of Taenitis blechnoides growing in the same location for comparison. Fortunately, the park was near my place and I need not hold my curiosity for too long. The fern was indeed Taenitis interrupta:
As for Taenitis blechnoides (pictures below), the sori are located much further away from the edge of the fronds. Also, the colour of the mature sori is dark orange though I cannot be certain whether the sori colours were due to the lighting condition or they really are different in colour.
Another differentiating feature between the 2 ferns is probably the sori arrangement at the tip of the frond. In Taenitis blechnoides, there seem to be no sori near the tip region while in Taenitis interrupta, the sori tend to extend all the way to end of the tip.
The DNA of Singapore website has listed the common name of Taenitis blechnoides as Bamboo Fern. The name can probably be used for similar-looking ferns such as Taenitis interrupta. The fronds of these ferns do look like bamboo leaves. Amazingly, I had been walking by the same Taenitis interrupta fern for more than 3 years whenever I visited the park but had never thought that it might be something new to me.
Besides the 2 Taenitis species, the park also housed another look-alike fern, Graceful Necklace Fern (Lindsaea ensifolia) although it is far less common than Taenitis blechnoides. This was another fern that I had overlook and confused it again with Taenitis blechnoides. It was not until January 2012 that I learned about Lindsaea ensifolia from someone who visited my website. The main differentiating feature of this fern from the 2 Taenitis species is the position of the sori. The sori of Lindsaea ensifolia is lined up along the edge of the fronds. After I knew about its existence, it turned out to be more common than I had thought. When you know what you are looking for, you tend to find it.
Unfortunately, the few colonies of Lindsaea ensifolia found in the park were located at an open space by the side of a track where routine grass pruning took place about once a month. Hence, mature fern like those seen in the forest are rare. But, the fern had persisted and adapted well by producing spores at an early stage when the fern was still small in size.
Although ferns may not be as exciting as the flowering plants to many people, they have become a rather fascinating group of plants in my quest of understanding how nature works.
Do visit my collection of fern pictures if you are keen to know other ferns that are available in Singapore!
Last updated: 18 May 2013