In Sheaths and Scabbards in England AD400-1100 by Esther A Cameron, the wood core species has been analysed for all the known finds in England. She states the "strong evidence for the standardisation in the selection of of wood species" and the stats are as follows:

Willow/Poplar 64%
Alder 17%
And the remainder consisting of a mixture of hazel lime beech birch and ash 19%

Willow and Poplar are archaeologically indistinguishable and therefore either could be the most popular wood core or both used equally. However she also notes the advantages of Willow as being light, fine, straight grained and resilient whilst Poplar is soft and light. Also haveing spoken to a tree surgeon and craftsman who agrees that Willow would be the far superior material for wooden scabbard cores.

I know poplar is commonly used by sword collectors as a wooden core as it is relatively easy to get hold of, however would this have been the most accurate material?

Please reply with evidence, sources and thoughts you may have on the subject.

Thanks,
Johnny Horn