This possibly could be C. griffithii (I thought I do see some tinges of redness below the leaves) which is recorded as a native species in Singapore by the crypts pages, finally!
Could this be a submersed C. x timahensis (i.e. transplanted to this place from Bukit Timah Hill since this species could really fetch very good money for the aquatic plant farms nearby)? If yes, this is another not only native but endemic species of Singapore according to the crypts pages!
I was lucky to managed to find a spathe of C. pontederiifolia there too. The crypts pages recorded its distribution as only in West Sumatra. Is this likely be an introduced species too or could this possibly be a native species since Sumatra is actually not as far from Singapore as compared to Sri Lanka?
The above are just pure speculations and if I identified any of the species shown in these old photographs wrongly, do let me know and sorry for the errors.