The Collaborative International Dictionary
Procambium
Procambium \Pro*cam"bi*um\, n. [NL. See Pro-, and Cambium.]
(Bot.)
The young tissue of a fibrovascular bundle before its
component cells have begun to be differentiated.
--Sachs.
Wiktionary
procambium
n. (context botany English) A meristem that lies just inside the protoderm and develops into primary xylem and primary phloem.