Graniferous tracheary elements in the haustorium of the santalaceae

Abstract

Haustoria of santalaceous root parasites examined have unusual tracheary elements containing granules within their lumina. Benson (1910) thought the granules were starch and that the cells also contained an enucleate protoplast. She believed the cells combined the functions of phloem and xylem conduits and so named them "phloeotracheides" (sic). In contrast, our research has shown the cells are dead at maturity and that the granules arise during ontogeny from the endoplasmic reticulum and are proteinaceous. We have re-named the cells graniferous trancheary elements.