The structure and cytochemistry of the pistil of Sternbergia lutea (Amaryllidaceae)

Abstract

Studies were carried out on structural and cytochemical aspects of the pistil of Sternbergia lutea (L.) KerGawl. The stigma is of the wet papillate type; the papillae are unicellular and are arranged densely around the rim of a funnel-shaped stigma. The stigma exudate is limited and is confined to the bases of the papillae and the inner lining of the stigma. The papillae are smooth in the distal part and are covered with intact cuticle-pellicle lining. The cuticle is disrupted at places towards the base of the papillae releasing the exudate. The exudate is rich in pectins and other polysaccharides but poor in proteins and lipids. The papillae show dense cytoplasmic profiles with extensive endoplasmic reticulum (ER), abundant mitochondria, polyribosomes and active dictyosomes. The style is hollow. The stylar cavity is surrounded by two to four layers of glandular cells. In the young pistil the canal is lined with a continuous cuticle, but in the mature pistil the cuticle becomes disrupted and the canal is filled with the secretion produced by the cells of the surrounding glandular tissue. Ultrastructurally, the cells of the glandular tissue are very similar to the stigmatic papillae. The inner tangential wall of the cells bordering the canal is uniformly thicker than other walls. The secretion in the stylar canal, as well as the intercellular spaces of the glandular tissue, stain intensely for pectins and polysaccharides but poorly for proteins and lipids. Pollen tubes grow through the stylar canal. Structural and cytochemical details of the pistil of Sternbergia are compared with other hollow-styled systems.