alburnum

Alburnum, al-burn′um, n. in trees, the white and soft parts of wood between the inner bark and the heart-wood.

Old wood, with black bark and with little of the white alburnum, is preferred.

Darwin possesses the epidermis of poetry but not the cutis; the cortex without the liber, alburnum, lignum, or medulla.

The tree was evidently hollow throughout its length; but perhaps some portion of the alburnum still remained intact.

It is through the alburnum that the ascending sap chiefly flows.