Blechnum vulcanicum
Content
Distribution
Asia-Tropical: Borneo present (Sabah present); Jawa (Jawa present); Lesser Sunda Is. present; Philippines (Philippines present); Sulawesi (Sulawesi present); Sumatera (Sumatera present), Bonthain present, Bougainville present, E Highlands present, Flores present, G. Singgalan present, Gedé present, Kandang Badak present, Luzon present, Mt Kinabalu present, Mt Wilhelm present, New Ireland present, Northern Papua present, Papua New Guinea present, W slopes of Mt Kenivem present, head of Columbon river present, subdist. Kokoda present
Malesia: Sumatra (G. Singgalan), Borneo (Sabah: head of Columbon river, Mt Kinabalu), Java (Gedé: Kandang Badak), Philippines (Luzon), Sulawesi (Bonthain), Lesser Sunda Islands (Flores), Papua New Guinea: E Highlands (Mt Wilhelm), Northern Papua (subdist. Kokoda, W slopes of Mt Kenivem), New Ireland, Bougainville. Outside Malesia: Widespread but rarely common and in many locations regarded as extremely rare. A number of specific, subspecific, and varietal names have been applied to geographically isolated populations and certainly some merit recognition but others defy satisfactory definition. The group is currently the subject of a separate study.
Notes
1. Named vulcanicum from its original type locality on a volcano but not restricted to such places. The holotype was not found.
2. The Malesian material of B. vulcanicum, although showing considerable variation, is considered as belonging to a single taxon. The specimens are usually densely pilose especially on the abaxial surfaces of the costae and veins and usually also the rhachis. Some populations completely lack hairs at the base of the stipe in the zone of persistent scales. The hairs of the Malesian material tend to be pale brown or fawn coloured while those from further south, outside Malesia, tend to have paler often silvery white hairs.
3. There is a wide range of frond size through the Malesian region; generally plants with larger sterile fronds tend to have pinnae with acuminate apices while those with smaller fronds tend to have pinnae with blunt obtuse apices. Very large sterile fronds tend to have up to 5 pairs of basal pinnae not fully adnate to the rhachis and strongly deflexed. There is considerable variation between populations in the distribution of hairs on the fertile pinnae, many almost completely lacking these, but others with their abaxial costae and sometimes also their indusia densely pilose.
4. The taxonomy of B. vulcanicum and the closely related taxa is complex. It could be argued either that the whole group should be regarded as one Linnaean species, or that there are several taxa. However, careful study of the available collections suggests that only a few of the variants are sufficiently distinctive and constant to justify separate taxonomic status. These are outside the Malesian region and will be dealt with in a separate paper.
2. The Malesian material of B. vulcanicum, although showing considerable variation, is considered as belonging to a single taxon. The specimens are usually densely pilose especially on the abaxial surfaces of the costae and veins and usually also the rhachis. Some populations completely lack hairs at the base of the stipe in the zone of persistent scales. The hairs of the Malesian material tend to be pale brown or fawn coloured while those from further south, outside Malesia, tend to have paler often silvery white hairs.
3. There is a wide range of frond size through the Malesian region; generally plants with larger sterile fronds tend to have pinnae with acuminate apices while those with smaller fronds tend to have pinnae with blunt obtuse apices. Very large sterile fronds tend to have up to 5 pairs of basal pinnae not fully adnate to the rhachis and strongly deflexed. There is considerable variation between populations in the distribution of hairs on the fertile pinnae, many almost completely lacking these, but others with their abaxial costae and sometimes also their indusia densely pilose.
4. The taxonomy of B. vulcanicum and the closely related taxa is complex. It could be argued either that the whole group should be regarded as one Linnaean species, or that there are several taxa. However, careful study of the available collections suggests that only a few of the variants are sufficiently distinctive and constant to justify separate taxonomic status. These are outside the Malesian region and will be dealt with in a separate paper.