Vertical Section Of A Stoma

pore epidermis ouard cell exerts an upward pull on the water columns present in the vessels of the xylem so that the leaf is continually supplied with water.

Parts of the leaf. Basically a leaf possesses a thin flat green blade or lamina borne on a thin staik or petiole. When the petiole is absent the leaf is desciibed as sessile. The lea! is attached to the stem by its swollen leaf base. In some species small flattened structures, the stipules, ara present on either side of the leaf base. There is always an axillary bud in the inner angle between the leaf base and the stem. Insertion of leaves. Leaves are attached at nodes which are separated by lengths of stem, the internodes. There may be a single leaf at each node (alternate), two (opposite) or more than two (verticiliate).

Types of leaves. Leaves can be separated into two kinds, simple and compound. Simple leaves have a single lamina, but as the diagrams on the fol-.«mar* bud |owing pages show this

veins

Petiole lamina.

veins

Petiole

Vertical Section Leaf
ON THE STEM

varies greatly in shape. It may be deeply lobed but never consists of separate areas, tn contrast the compound leaf has a number of distinct leaflets which may be arranged tn one or two ways. Compound p/'/inaie leaves have leaflets borne In two rows on either side of a continuation of the petiole, the rachis. Where a single leaflettermlnates the rachis the leaf is described as imparipinnate, but if there are two leaflets at the tip it is pan-pinnate. The number and shape of the leaflets may vary even on the same

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  • brigida
    What is the vertical section of leaf?
    8 years ago

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