Fig. 1: Flowering woody climber (Fissistigma ovoideum) and petals of flowers on the forest floor

Having received information about a population of flowering Fissistigma ovoideum high up on a Tembusu tree along the TreeTop Walk Trail, I proceeded to the trail on Tuesday (1 April) to investigate. Observing the flowers of this woody climber is a rare opportunity, as it typically flowers on tall trees. Until now, I have only encountered young plants that are challenging to identify due to the numerous similar species found on the forest floor. Ultimately, I managed to obtain some images with satisfactory quality despite the distance of the flowering stalks from the ground, as well as images of fallen petals (Fig. 1). Although I observed the flowers from a distance, I am quite pleased with the chance to witness such a rare event involving this climber.

During the walk, the weather conditions were favourable, and there were no rain showers. The temperature increased markedly around midday when I traversed the tree-top bridge. In total, I spent approximately five hours on the trail, making frequent stops to examine various noteworthy observations and to capture images.

Fig. 2: Fallen branches, leaves and flower buds of Garcinia species

Due to recent strong wind and rainy weather conditions, large piles of cleared fallen trees were disposed by the side of the boardwalk at two separate locations. The remains of the fallen trees appeared fresh, indicating they fell recently. One pile was from a tree that appears to be of the Garcinia species (family Clusiaceae), with flower buds visible on some branches (Fig. 2).

(a) Oxyceros bispinosus	(b) Dissochaeta biligulata	(c) Artabotrys maingayi
Fig. 3 (a-c): Three climbers found among the fallen tree(s)

The second pile presented a more intriguing mix of plant species. I was unable to identify the fallen tree(s) due to the dense coverage by various climbers. Upon closer inspection, I discovered three climbers (Fig. 3) that were of particular interest. The first climber, Oxyceros bispinosus, exhibited several bundles of fruits. Last year, during my visits, I observed a flowering specimen from the tree-top bridge. Since then, the flowers had transformed into fruit, although it was too distant from the bridge to capture high-quality images. The second climber, Dissochaeta biligulata, displayed three flower buds. Initially, I had identified it as Dissochaeta intermedia, which, according to the 2022 Singapore flora checklist, is a misapplied name. The third climber, Artabotrys maingayi, featured a partially damaged flower and small immature fruits. This one is a new addition to my website.

There were more fallen items on the forest floor along the trail. Three of them that caught my attention (Fig. 4) were the fruits from Calophyllum ferrugineum and Aspidopterys concava, and flowers from Sandoricum koetjape. The fruits and flowers were found littering the forest floor at specific locations. Due to the height and crowded canopy, I could not spot the parent plants high up on the trees. However, I observed a fruiting Calophyllum ferrugineum tree near the end of the tree-top bridge. Additionally, there was a fruiting Calophyllum tetrapterum tree (Fig. 4) after the entrance to the bridge. This is the second new plant added to my website from this trip.

(a) Calophyllum ferrugineum	(b) Aspidopterys concava	(c) Sandoricum koetjape	(d) Calophyllum tetrapterum
Fig. 4 (a-d): Fallen fruits and flowers from 3 plants and a fruiting Calophyllum tetrapterum

(a) Ardisia complanata	(b) Litsea accedens
Fig. 5 (a-b): Two flowering plants

Among the numerous flowering plants observed along the trail, I found particular interest in two species: Ardisia complanata with its distinctive white flowers (Fig. 5) and a few Litsea accedens which had started to produce flower buds. The last time I observed a fruiting Ardisia complanata was in April 2023. Litsea accedens appears to flower more frequently, as I encountered flowering specimens along the same trail last year; however, I only observed the fruits once back in December 2015.

Last year, I made a total of nine trips to the TreeTop Walk Trail between August and October, with the last trip on 29 October 2024. After that, I paused my visits to this trail until the current visit. It is always good to be back on the trail again.