This type of bark breaks off of roots very easily, and it is almost impossible to dissect a root, fix and process it and still have very much bark left on the root – most has fallen off during handling because the phellem layers are so fragile. These sclereids have rather thin secondary walls, but in some species, they can have walls so thick there is almost no lumen left. These cells are shown in tangential section in following micrographs. |