PLANTS OF THE INDIAN DESERT. 167
mesophyll. Bundle-sheaths, when present, internal. Isolated sub- epidermal girders below all larger veins and those on the upper side developed alternately above the larger veins. T. S. of the axis trian- gular. Of sub-epidermal girders in the axis, larger ones alternating with smaller ones. Assimilatory tissue forming arcs or girders of palisade cells round the peripheral bundles. Ground tissue differ- entiated in the centre into pith.
Fimbristylis tenera Boeck.— Fig. 308. Margins angular, the two angles supported by stereome bundles. Upper epidermal cells forming articulation tissue. Stomata only on the lower surface. Front cavity elevated above the surface. Veins embedded and arranged in a single row in the middle. Bundle-sheaths when present internal. Mechanical tissue in the leaf in the form of isolated sub-epidermal girders on the upper surface, at the angles of the margin and on the lower side of the mid-rib. T. S. of the axis circular and grooved. Assimilatory tissue in form of arcs or girders of palisade cells round the peripheral bundles. Vascular bundles below the furrows larger and longer and without protecting stereome girders. Mechanical tissue in the axis in the form of isolated sub-epidermal girders in the ribs. Ground tissue not differentiated in the centre into pith.
Scirpus quinquefarius Ham. L— Figs. 309, 310. Leafless. T. S. of the axis circular. Front cavity on a level with the surface. Assimi- latory tissue of palisade cells below and between stereome bundles. Smaller vascular bundles peripheral and placed in the assimilatory tissue ; larger ones placed in the ground tissue. Bundles enclosed in an outer ring of polygonal colourless cells and an inner ring of stone- colls. Mechanical tissue in the form of isolated sub-epidermal stereome girders. Ground tissue characterised by a system of very large air spaces.
(Tu be Continued).
