type of deciduous birch tree, (kokuji)
椣 refers to a specific type of deciduous birch tree. It is a kokuji, created in Japan to name this tree, so its meaning is narrow and concrete.
椣 is a Japanese kokuji, formed by combining 木 (tree) with 典, which likely contributes a phonetic element. It was created specifically to represent the shide birch tree.
The tree radical 木 beside 典 suggests a tree whose name sounds like 典. Picture a birch tree with leaves shaped like the strokes of 典.
For しで, imagine a birch tree shedding its bark in strips: the sound 'shide' echoes the rustling of the peeling bark. Shide -> しで.
—