catalpa tree, woodblock printing
梓 centers on the catalpa tree and its practical use: woodblock printing, which traditionally used catalpa wood for carving blocks.
梓 combines 木 (tree) with 辛, which likely contributes the sound and may relate to the catalpa tree's sharp or bitter properties. The exact historical development is uncertain.
A tree (木) with a sharp, bitter character (辛) is the catalpa, whose wood is used for carving printing blocks.
For シ, imagine a sheet of paper printed from a catalpa woodblock: sheet -> シ, and the tree provides the printing surface.
Japanese cherry birch (Betula grossa)
wood-block printing
to bring (a book) into the world; to publish
cabinetmaker; woodworker
Emperor's coffin (made of catalpa wood)
female medium who summons spirits by sounding the string of a catalpa bow
catalpa bow; spirit bow; bow used to summon spirits, made of Japanese cherry birch, catalpa, or other wood
(precious) letter; love letter