Weekly Series
Nature Weekly
Short Notes on Nature Singapore

26 March 2017 | Marsh Water-willow | Justicia comata |

photo In February, I received a series of queries from someone on the identity of some Thailand plants. From the more than 10 different plant pictures shared, I could only provide clues on half of them. While searching around for the identities of the plants, I came across a book titled "Flowering Plants of Thailand: A Field Guide" by Patrick D. McMakin first published in 1988 with the fourth expanded edition in 2009. Though it might seem to be an old book, I doubt there would be drastic changes to the plant varieties back then compared to the available current days' species. I placed the order and the book took just 2 weeks to arrive.

photo I browsed through the pictures in the book but did not find anything related to the unknown plant pictures that I was shown previously. Many of the plants illustrated in the books are also available in Singapore. One picture did caught my attention. It was a plant labelled as Andrographis paniculata and was placed in the section for Freshwater Marsh plants in page 85 of the book. This was the only picture of this plant in the entire book. I knew Andrographis paniculata (King of Bitters) very well since I had plenty of them in my pots. Though the flowers in the picture was not too clear due to the size of the picture, it was quite obvious from the overall appearance of the flower stalks that the plant had to be the Marsh Water-willow (Justicia comata) instead.

Marsh Water-willow was a plant that I remembered well because it took me several years between first observation and it eventual identification. I could not recall exactly when the breakthrough happened. The source of its identity was revealed in the same plant field guide from Taiwan that helped me with the identification of Bellorita (Erigeron bellioides) --- see my weekly note in February. This time round, the much needed information was in page 40 of the field guide.

photo photo While Bellorita was first found very recently in January 2016 in Singapore, Marsh Water-willow was first seen much earlier in 2009. A 2010 publication from Taiwan [1] indicated that the origin of this plant was Tropical America and it was first record in Taiwan in 2006. A research [2] on powdery mildews in Thailand had mentioned the present of this plant in the Chiang Mai Province. The plant was not listed in the Singapore flora checklist published in 2009. So far, I had only seen it in one location here and I doubt its native-ness.


[1] Wu SH, Yang TYY, Teng YC, Chang CY, Yang KC, Hsieh CF. Insights of the latest naturalized flora of Taiwan: Change in the past eight years. Taiwania 2010;55(2):139-159. | Read article |

[2] Meeboon J, Hidayat I, Takamatsu S. Notes on powdery mildews (Erysiphales) in Thailand I. Podosphaera sect. Sphaerotheca. Plant Pathology & Quarantine 2016;6(2):142-174. | Read article |

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