I am pleased to present you today a new record for Singapore - Athyrium accedens (Family: Woodsiaceae). I have found a small population of this fern in Bukit Timah Nature Reserve.
The late Prof. R. E. Holttum described it as a fern of shady mountain stream-sides, found in Malaya only on the Main Range and Taiping Hills. The specimens that I discovered were also near a stream. They are about a meter in height - simply pinnate, tufted and erect, and producing plantlets (asexually) on the rachis besides the usual spores (for sexual reproduction).
Some major characteristics below:
Pinnae (leaflets) - up to 15 per frond (leaf)
Each plantlet arising from the pinna (leaflet) axil.
This mature plantlet is ready to drop off and grow on its own.
Size and shape of pinna: tipped and broad; margin crenate or shallowly lobed.
Sori linear, forming the characteristic V-shaped arrangement.
Close-ups of sori (group or arrangement of spore cases / sporangia).
Stipe (stalk /stem) green, covered with minute and spiky protuberances.
Close-up of the protuberances: each one is actually a remnant stalk that has held a scale (thin membranous hair).
The rachis (branch extending from stipe bearing pinnae / leaflets) is grooved above.
Footnote: A New Record is a species already known to science but not known to occur previously in a certain botanical area in question. Now that Athyrium accedens has been found occurring in its natural state here, it can be added to the flora of Singapore as a native species. So in total, we have now 11 species of Athyrium in Singapore.