Indian balsam root. Light micrograph of a transverse section through the root of an Indian balsam (Impatiens glandulifera) plant,showing primary succulent tissue. From outer root to centre: single layer of epidermis (red); cortex of parenchyma,with large cells storing water (blue); ring of pericycle (dark-violet). In the centre of the root there is no pith,but xylem,primary metaxylem (large vessels,red) and protoxylem made up of star-shaped arms (small cells,red). Next is the primary phloem,in-between the xylem (small cells,blue),with sieve tubes. Magnification: x37 when printed 10 centimetres wide |