The flora of Singapore
H. N. Ridley, Director of the Singapore Botanic Gardens, published this comprehensive flora of Singapore island and its small surrounding islets in 1900, providing the first systematic enumeration of the island’s plant life at a time when rapid deforestation was erasing the original forest cover. The work documents over 1,900 species of flowering plants and more than 130 ferns within an area of barely 200 square miles, establishing Singapore as a site of exceptional floristic density for its size.
Summary
Ridley opens with a geological and ecological survey of the island, correcting earlier mischaracterisations by J. R. Logan (1846) who had confused sedimentary deposits with volcanic rock. He describes the grey granite hills (Bukit Timah, Bukit Mandai, Tanjong Gol) and the overlying sedimentary clays and gravels, then maps the remaining vegetation types: primary jungle tracts dominated by Dipterocarps, Dyera, Irvingia, and other large canopy trees; mangrove fringes along tidal rivers; a distinct sandy coastal flora from Tanjong Ru to Changi; secondary growth (belukar) of Macaranga, Rhodamnia, and Melastoma; and vast expanses of lalang (Imperata cylindrica) on abandoned cultivation. He notes that many place-names preserve the memory of trees now extinct or rare in the locality—Kranji (Dialium), Changi (Balanocarpus), Tampenis (Sloetia sideroxylon), Kampong Gelam (Melaleuca)—and that most of Wallich’s 1822 collections can still be recovered, though some were probably mislabelled from Penang.
The middle sections address phenology and pollination ecology. Ridley documents the absence of a true dry season, the synchronous flowering of Dipterocarps at five-year intervals, the precise periodicity of Dendrobium crumenatum (the Pigeon Orchid), and the relationship between flower colour and pollinator type—fly-pollinated flowers being small, green or whitish, and often malodorous, while butterfly- and bee-pollinated flowers are white or pink in large panicles. He also identifies several introduced weeds of South American origin (Clitoria cajanifolia, Cleome aculeata, Lantana camara, Hyptis suaveolens) that were absent from Wallich’s 1822 collection, indicating their arrival in the intervening decades.
The bulk of the paper is a family-by-family enumeration of species with localities, brief descriptions, and notes on economic or medicinal uses. Ridley marks endemic species with an asterisk and includes introduced or doubtful plants in brackets. He reviews the contributions of earlier collectors—Raffles, Jack, Wallich, Cuming, Lobb, Maingay, Schomburgk, Anderson, Hullett, and Cantley—flagging numerous mislocalisations in the literature, particularly in the Flora of British India, where plants labelled “Singapore” were in fact from Penang or Malacca.
Key Findings
- Singapore’s flora comprises over 1,900 species of flowering plants and over 130 species of ferns within approximately 200 square miles, a density Ridley contrasts with the 1,200 flowering species of the British Isles across 121,115 square miles (p. 31).
- The most extensively represented orders are Euphorbiaceae, Urticaceae, Rubiaceae, and Orchidaceae; the largest genera are Ficus (35 species) and Myristica (p. 30).
- Dipterocarps flower synchronously only once every five years, coinciding with a period of higher temperature and greater dryness in May or June; all individuals in a given district flower on the same day (p. 32).
- The first Botanic Garden was established by Nathaniel Wallich in November 1822, comprising 48 acres including the Government Garden on Fort Canning Hill; it was later abolished and no trace remains (p. 34).
- Several species are recorded as endemic to Singapore, including Shorea gratissima, Shorea rigida, Kunstleria ridleyi, Spatholobus ridleyi, and numerous orchids and ferns marked with an asterisk throughout the list (pp. 49–196).
- The sandy coastal tract from Tanjong Ru to Changi supports a distinct flora rich in grasses, sedges, Xyris, Cyanotis, Rhodomyrtus, and Vaccinium, much of which has been lost to coconut cultivation except at Changi Point (p. 29).
Conclusion
Ridley’s flora serves as both a taxonomic inventory and an ecological baseline recorded at the moment when Singapore’s primary forest was already largely destroyed. His definitive takeaway is that the island, despite its small area and low elevation, supports a floristically rich and geographically distinct Malayan flora of considerable scientific interest, one that was being rapidly diminished by cultivation and that required urgent documentation before the remaining primary tracts disappeared.
Context
- Ridley wrote as Director of the Singapore Botanic Gardens (appointed 1887), drawing on his own collections and those of native collectors employed at the Gardens; the work represents the culmination of his fieldwork on the island over more than a decade.
- The study’s principal archival basis is the Botanic Gardens Herbarium in Singapore, supplemented by Wallich’s catalogue, King’s Materials for a Flora of the Indian Archipelago, and the herbaria at Kew and Calcutta; it stands as the definitive pre-modern flora of Singapore and remains a key reference for historical biogeography of the Straits region.