Fig. 1: Flower of Mecardonia procumbens (Yellow-flowered Waterhyssop)

On 11 February, I was pleased to discover another new wild plant. It is a small, low-lying herbaceous plant found growing in a groove of an open-air carpark lot. Its presence would have gone unnoticed if not for its single tiny yellow flower (Fig. 1). This marks the third new plant that I have identified in this carpark area. The previous two discoveries were made in June 2015 and January 2016.

Based on its overall appearance, the plant appears to be a member of the family Linderniaceae. However, none of the species within this family listed on my website possess yellow flowers. A review of the same family in the most recent Singapore flora checklist did not provide any additional information. An online search suggested Torenia flava (Yellow-flowered Torenia) as a possible match. Nevertheless, the flower shape of Torenia flava differs from that of the plant I discovered.

To ensure there were no other potential candidates, I reviewed the Torenia species observations on the iNaturalist website. While nothing matched closely, I took the opportunity to suggest the correct identification of a plant (Centranthera tranquebarica), which I believe was mistakenly classified as a Torenia species. Centranthera tranquebarica is an extremely rare grassland parasitic plant in Singapore. As of 23 February, there was only one observation from Singapore recorded on the iNaturalist website.

Fig. 2: The plant retrieved from the carpark lot

Meanwhile, I had retrieved the entire unknown plant (Fig. 2) and re-planted it in my pot. It appeared damaged with many leaves affected, likely due to pressure from vehicle wheels and people stepping on it. Fortunately, the flower was intact when I found it. The flower detached from the plant the next day.

After several days, while the unidentified plant was adapting well in my pot, I still had not managed to confirm its identity. I decided to search for information using Chinese terms “Linderniaceae (母草科)” and “yellow flower (黄花)”. To my satisfaction, I found two images of yellow flowers that perfectly matched the plant I discovered. The plant was finally identified as Mecardonia procumbens (Yellow-flowered Waterhyssop), which belongs to the family Plantaginaceae. According to the latest Singapore flora checklist, this species is considered naturalised in Singapore. It was officially reported in Singapore in 2018 [1], based on a specimen collected from the Katib area in December 2017. On the iNaturalist website, there were four observations from Singapore, with the earliest observation dating back to December 2021.

Local websites such as Urban Forest and the Biodiversity of Singapore have documented this plant several years ago. However, it seems to be an uncommon plant as it has not been widely encountered until now. The newly discovered plant will be kept in the pot for observation. It is anticipated that additional photographs of the plant can be taken as it becomes healthier and begins to flower again.

Reference:

[1] Chen LMJ, Ho BC, Choo LM, Koh SL. Additions to the Flora of Singapore, new and overlooked records of naturalised plant species (1). Gardens' Bulletin Singapore 2018;70(1):91-101. | Read article |