One of the words given as a solution to Saturdays Scrabble Gram is CAMBIA. I've looked in all my dictionaries (inc the 2 volume Shorter Oxford) but can find no mention of CAMBIA. Does anyone know what it means.
cambium noun (cambia or cambiums) bot in the roots and stems of woody plants: a layer of actively dividing cells between the xylem and the phloem, which produces an increase in lateral growth or girth. ETYMOLOGY: 17c: Latin, meaning 'exchange'.