Structural and cytochemical analysis of the stigma and style in Tibouchina semidecandra Cogn. (Melastomataceae)
1995
Ciampolini, F. | Faleri, C. | Cresti, M.
Structural and cytochemical aspects of the pistil of Tibouchina semidecandra Cogn. were studied. The stigma is of the wet-papillate type and is structurally divisible into a papillar zone and a stigmatic zone. The papillar zone consists of loosely arranged papillae which are matchstick-shaped, unicellular, and produce lipid droplets that remain entrapped below the thick cuticle. The bulk of cell volume is made up of large vacuoles rich in tannin. The stigmatic zone consists of layers of secretory cells with dense cytoplasm, actively secreting dictyosomes and numerous rough endoplasmic reticulum (RER) profiles. Free-flowing lipid exudate, produced by these cells, is initially stored in the intercellular spaces, and subsequently extruded out to cover the surface. The style is solid with a core of transmitting tissue traversing its whole length. The transmitting tissue consists of loosely arranged cells with numerous organelles and conspicuous intercellular substance rich in polysaccharides and pectins. Ultrastructural details indicate that the intercellular secretion is accompanied with fraying of the wall component. Both the transverse and longitudinal walls contain plasmodesmata.
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