Development and Ultrastructure of Foliar Glands of Comptonia peregrina (Myricaceae)

Capitate-stalked glands of Comptonia peregrina (L.) Coulter are initiated by enlargement and papillation of individual epidermal cells. Subsequent periclinal divisions result in formation of a uniseriate stalk of two to four cells. A secretory disk is initiated by an anticlinal division of the distal stalk cell. Additional anticlinal and periclinal divisions result in formation of a two-tiered multicellular secretory disk. Secretory disk cells have dense cytoplasm with numerous plastids and large nuclei with prominent nucleoli. Vacuoles are large and contain a dense osmiophilic material along the tonoplast. Mature vacuoles are occluded with this material. Separation and distension of the cuticle from the cell walls of the secretory disk occur with the onset of secretion. Degeneration of the cytoplasm and organelles characterizes the secretory cells of the senescing foliar gland.