Ophioglossum reticulatum
[Adder's Tongue Fern]

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In June 2015, a lone fern appeared in one of my pots (see pictures below). It had 2 non-fertile leaves (known as trophophyll or trophophore). The long erected fertile stalk was an extension of the stalk from the non-fertile leaf. At the end region of the fertile was a spike where paired sporangia (spore-containing bodies) lined its length. Its leaves were more elongated than those seen previously.

In the 2009 Singapore flora checklist, there were 3 species of Tongue Fern listed, namely Ophioglossum nudicaule, Ophioglossum pendulum and Ophioglossum reticulatum. Ophioglossum pendulum usually grows on trees and is much larger in size than the other 2 Tongue Fern. According to the Flora of North America website, Ophioglossum nudicaule has 5-12 pairs of sporangia. As for Ophioglossum reticulatum, the number of sporangia was indicated to be 20-45 pairs by the Flora of Zimbabwe website. Based on the sporangia count and having only 2 choices left, this fern is identified as Ophioglossum reticulatum.

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Close-up views:

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Reference:

[1] Sinha BMB, Srivastava DP, Jha J. Occurrence of various cytotypes of Ophioglossum reticulatum L. in a population from N. E. India. Caryologia 2009;32(2):135-146. | Read article |