Fig. 1: Inflorescences of unknown grass species

Fig. 2: Spikelets of unknown grass species

This week, I revisited the nearby park with the objective of identifying wild grass species from the family Poaceae that are new to me. This is the same park where I recently documented the Tropical Finger-grass (Digitaria ciliaris) described last week. Numerous grass species are concentrated along the sides of a serpentine path leading to the summit of this elevated park. After surveying several species, I identified an unknown grass species that warrants further investigation (Fig. 1).

The spikelets of this species (Fig. 2) have a distinctive shape not observed in other grass species encountered to date. Each spikelet, approximately 2 millimeters in length, resembles an inverted shoe held up by a fine curvy stalk, similar to a piece of artwork. All parts of the plant, including the node, sheath, and collar, are nearly hairless. From a distance, the inflorescence arrangement on the culm of this unidentified grass resembles that of Steinchisma laxum (Lax Panicgrass), which is also found in the same park. However, closer examination of each spikelet reveals differences; the spikelet of Steinchisma laxum has the typical elongated oval shape common to many grass species (Fig. 3).

Fig. 3: Spikelets of Steinchisma laxum

Without having any information about the genus of this unknown species, I decided to go through the list of species in the Poaceae section in the latest Singapore flora checklist and check their images on the iNaturalist website. The goal was to identify the grass specimen or at least narrow it down to the genus level. After reviewing all available images of the 130 species plus the 6 varieties listed, none matched the specimen. However, this process revealed some incorrect identifications of grass species on my website, which allowed me to correct the botanical names for at least five of them.

During my review of grass images on the iNaturalist website, I also compiled the number of records from Singapore for all species listed in the Singapore flora checklist. This provided insight into the commonly reported grass species. The top three observations as of 20 April 2025, were Axonopus compressus (94 records), Imperata cylindrica (91 records), and Ischaemum muticum (50 records). The ranking of these species was expected, as they are easily identifiable.

I will store the set of images of this unidentified grass species in my archive folder for the time being.