Ultrastructural aspects of three glandular trichome types of <i>Pogostemon cablin</i>.

<p>(A–C) Short-stalked capitate trichomes in secretory stage: (A) the glandular trichomes with two head cells (HC), a narrow stalk cell (SC) and a basal cell (BC) and the sub-cuticular space (SCS); (B) portion of head cell showing Golgi (G) and plastids (P) in close contact with rough endoplasmic reticulum (RER) near cell wall (CW); (C) numerous Golgi (G) with many vesicles near the plasma membrane (PM). (D–F) Peltate glandular trichomes in secretory stage: (D) longitudinal section through a secretory peltate glandular trichome with plentiful electron-light lipid deposits (_*) in the sub-cuticular space; (E) the higher magnification of (D) showing Golgi (G) and plastids (P) in close contact with the short segments of smooth endoplasmic reticulum (SER); (F) vesicles (arrows) are found between cell wall (CW) and plasma membrane (PM). (G–K) Ultrastructural aspects of the long-stalked capitate trichomes: (G) the mature glandular trichomes with a cytoplasmically dense apical cell, a narrow stalk cell and an elongated vacuolated stalk cell; (H) the higher magnification of (G) showing the secretory cell with the sub-cuticular space (SCS), many small vacuoles (V), abandent mitochondria (M) and numerous small plastids (P); (I) the details of the cytoplasm of the secretory cell showing prevalence of mitochondria (M) and plastids (P) with plastoglobuli in the apical region; (J) the sparse smooth endoplasmic reticulum (SER) close to a lipid-filled plastid (P) (arrow); (K) a bigger vesicle (arrow) between cell wall (CW) and plasma membrane (PM).