Parenchyma & Collenchyma





I.          Parenchyma:


A.                 Preserved material of Sanseveria cylindrica that shows ground parenchyma with secondary wall thickenings.  Make free-hand cross-sectional cuts to reveal the cells and walls.


B.         Kiwi fruit - thin sections and smears of ground tissue will show storage of lipids (oil droplets) and starch.  Prepare slides showing the cells as separate as possible, and with some, use IKI stain to reveal the presence of starch.  This material should show birefringence with polarizing light.



II.        Collenchyma:


A.        Apium, celery - mount a thin cross-section from fresh material of the thickened petioles and observe the collenchyma in polarized and unpolarized light.  Then replace the water with 0.25% aqueous methylene blue.  Repeat with a fresh section stained with 0.05% aqueous toluidine blue 0 to compare these two staining methods.  Also, see if you can find oil ducts in the vascular regions.  Make electronic micrographs of good preparations.


            Optional:      Mount a fresh transection in 95% ethanol and observe the effect on the collenchyma cell walls.  The change takes a minute or two.


            B.         Apium - mount macerated collenchyma cells in methylene blue solution and observe angular collenchyma.


            C.         Collenchyma "types."  Section the following (pith or carrot may help in some cases) and determine which type of collenchyma is present.


                        1.         Preserved stems of Cichorium intybus  (chicory)

                        2.         Preserved petioles of Daucus sp. (carrot), annular collenchyma

                        3.         Eupatorium sp. lamellar collenchyma

                        4.         Preserved stems of Datura sp. (Jimson weed) for lacunar collenchyma


D.        Prepared slides of Ricinus (Castor bean) stem transections.  Those identified as "young stems" are best.  What type of collenchyma is present?