the.com/cambium
The tree's hidden one-cell-thick assembly line, quietly building everything you call wood.
means A thin layer of living cells beneath bark that divides to grow new wood inward and bark outward.
from From Medieval Latin cambium, meaning exchange or change — the layer where a tree trades old growth for new, swapping cells outward and inward yearly.
Ring makerEvery annual tree ring is its handiwork.
Razor thinOften just one cell layer doing all the work.
Graft glueGrafting only takes when two cambiums align.