The fern-allies and Characeae of the Malay Peninsula
H. N. Ridley, Director of the Singapore Botanic Gardens, published this floristic treatment of the fern-allies and Characeae of the Malay Peninsula in 1919, providing a systematic account of the Lycopodiaceae, Selaginellaceae, Rhizocarpeae, and Characeae based on his own extensive field collections and examination of type specimens at Kew, the British Museum, and the Linnean Society. The work’s central argument concerns the striking contrast in endemism between the two major terrestrial groups: while no species of Lycopodium or Psilotum is endemic to the Peninsula, the Selaginella flora shows a remarkably high proportion of endemics, suggesting that the smaller, less widely dispersible spores of the latter group have permitted greater in-situ speciation.
Summary
Ridley structures the paper as a regional flora, treating each family in turn with diagnostic keys, species descriptions, locality records, and distributional notes. The Lycopodiaceae section covers thirteen species of Lycopodium and two of Psilotum, all of which possess wide tropical or circumglobal ranges. Ridley argues that the dust-like spores of these plants, combined with the great antiquity of the group, account for their cosmopolitan distributions; even the most restricted Lycopodium species extend across multiple continents. He notes that L. cernuum ranges from all warm countries to the Azores and New Zealand, and that P. triquetrum occurs from Florida to New Zealand, while P. complanatum is absent from the Indian Peninsula and Africa, suggesting a more island-oriented dispersal history (p. 139–140).
The Selaginella section constitutes the bulk of the paper and its most significant contribution. Of thirty-two species recorded, twenty-one are classified as endemic to the Malay Peninsula, with only a handful extending into India, the Malay Isles more broadly, or the tropics generally. Ridley acknowledges that further collecting in Borneo and Sumatra may reduce the number of true endemics, but he found no specimens or reliable records of the endemic species in the Kew or British Museum herbaria (p. 140). He describes several new species from his own collections, including S. cuprea, S. illustris, S. reptans, S. scabrida, and S. montana, and offers taxonomic corrections to earlier determinations by Baker and Beddome, notably arguing that S. trichobasis has been misidentified as S. plumosa in the Kew Herbarium and that S. pinangensis is likely an escaped S. serpens native to the West Indies (pp. 152–153).
The Rhizocarpeae and Characeae receive briefer treatment. The aquatic ferns are few in number owing to the limited availability of suitable localities, and Ridley notes that Azolla pinnata is probably an introduction from Java carried by Chinese pig-farmers who cultivate Pistia stratiotes (p. 140). The Characeae section records only four species across two genera (Nitella and Chara), and Ridley concedes that these plants have not been carefully collected in the Peninsula, relying on identifications by J. Groves (p. 162).
Key Findings
- Of 32 Selaginella species recorded for the Malay Peninsula, 21 are classified as endemic, 3 are shared with India only, 4 with Indo-Malaya, 2 with the Malay Isles only, and 1 (S. flabellata) ranges across all tropics except Africa (p. 140).
- No species of Lycopodium or Psilotum is endemic to the Peninsula; the most restricted Lycopodium species are confined to the Malay Isles (3 species) or to a range from Africa to Polynesia (3 species) (p. 140).
- Lycopodium cernuum is recorded from all warm countries to the Azores and New Zealand, occurring in the Peninsula from sea level to over 2,000 feet altitude, with distinct habitat variants (var. curvatum in dry xerophytic spots, var. salakense on wet mountains) (pp. 139–140, 144).
- Selaginella laevigata forms thickets of climbers often exceeding 30 feet in length, is common throughout open country and forest edges, and is known locally as Paku Salumah, Paku Lumut, and Paku Tanjong (p. 155).
- Selaginella trichobasis is described as “absolutely confined to the Malay Peninsula” and is common from sea level to 4,000 feet; Ridley argues it has been consistently misidentified as S. plumosa in the Kew Herbarium (p. 152–153).
- The Characeae are represented by only four species (three Nitella, one Chara), with Chara gymnopitys found “in vast abundance” in the Singapore Botanic Gardens lake (pp. 162–164).
Conclusion
Ridley’s definitive takeaway is that the fern-allies of the Malay Peninsula present a clear biogeographical gradient: the Lycopodiaceae, with their widely dispersible spores and ancient lineage, show essentially no endemism, whereas the Selaginellaceae, despite belonging to the same broad group of vascular cryptogams, have generated a substantial endemic flora—nearly two-thirds of the species being unique to the Peninsula. This pattern, Ridley implies, reflects the limited dispersal capacity of Selaginella spores relative to those of Lycopodium and Psilotum, allowing isolated populations to diverge in situ across the Peninsula’s varied topography.
Context
- Ridley wrote as Director of the Singapore Botanic Gardens (a colonial scientific institution), and the paper draws heavily on his own field collections from the 1890s through the 1910s, as well as specimens collected by colonial-era figures such as Col. Beddome, Bishop Hose, and the Curtis family.
- The work builds directly on Spring’s Monographie de la famille des Lycopodiaceae (1842–1849), Baker’s Fern-Allies (1887), and Van Rosenburgh’s Malayan Fern-Allies (1915), and represents the most comprehensive treatment of these groups for the Peninsula up to that date.