Pith

Pith is the central column of parenchyma cells found in the stems of most flowering plants. In young stems, pith may serve as storage tissue for starch and other nutrients. As stems mature, pith often deteriorates, leaving a hollow center (as in elderberry and bamboo). Pith characteristics — solid vs. hollow, white vs. brown, circular vs. star-shaped in cross-section — are useful for winter twig identification.