Anatomy of stylar head complex.
LM transverse and longitudinal sections illustrating the anatomy of the pollen presenter (p) and associated structures; GMA-embedded, stained with periodic acid Schiff/toluidine blue. (A) Segment of a transverse section through a flower bud showing position of corolla lobes (c) and a still intact anther (a) with four pollen-filled microsporangia, two of the latter appressed to, and fitting into the longitudinal grooves of, the centrally placed pollen presenter (p). Note ring of well-developed vascular tissue (vessels without stained contents) in central parts of the presenter. Epidermal cells (e) of the pollen presenter are radially elongated (appearing multiseriate due to slightly oblique angle of section). Note darkly stained cell wall thickenings of Igersheim, some indicated with thin (on outer and inner periclinal cell walls) or thick (bands encircling anticlinal cell walls) arrows. Pollen grains (pg) have similar darkly stained protruding onci (compare Figure 12). (B) Stylar head complex in longitudinal section to show the pollen presenter with recessed style. Note prominently enlarged and radially elongated epidermal cells, as well as the terminally placed stigma (s), the latter with a single adherent pollen grain; labels as in A.