Page 57 – Early stages of stomata and trichome formation
Fig. 50 . Early stages of stomata and trichome formation. Abaxial epidermis of the basal region of a tetraploid seedling leaf, A, and of a young, i.e., prechlorophyllaceous, leaf from the center of the leafy terminus of the stem (i.e., the so-called "crown" or "top"), B and C, to show the development of the stomata and trichomes. (Arrows indicate the direction of the main axis of the leaf), fu, furrow; lac, lateral accessory cell of etoma; mgc, mother cell from which stoma guard cells are formed; pac, polar accessory cell of stoma; ri, ridge; tac, trichome accessory cell; mtc, initial, or mother, cell of trichome; wc, wedge-shaped cell in lateral position to stoma mother cell — the presence of these wedge-shaped cells in the epidermis facilitates the location of the stomata at this early stage of development. (The cells forming the stoma and trichome structures are more heavily outlined to show their location). A, X340; B and C, X400.