Anatomy of the Strelitzia reginae flower (Strelitziaceae)

The Strelitzia reginae Ait. flower has many remarkable structural spezializations, the histology and cytology of which we have investigated. The chromoplasts of the sepals are conspicuously elongated and enclose numerous carotenoid tubules parallel to the long axis of the plastid. The petals have rounded – pearshaped leucoplasts with a rhomboid protein crystal and aggregated plastoglobules. The blue colour is confined to the epidermal cells, which contain vacuoles with anthocyanin. Prominent papillar processes from the petal epidermis give rise to brilliance through refraction. Various reinforcements occur within the flower parts. The perianth leaves have permeating fibre ribs and thickened epidermal walls. The stigma and the free part of the style consist mainly of fibre cells (with protoplasm). The base of the style and the ovary are enclosed in the receptacle, the epidermal and hypodermal cells of which have thickened walls. – The ground tissue of the basal part of the receptacle appears aerenchymatous. There are also idioblasts containing raphides, druses, and tannin. The secretory cells of the stigma are long unicellular hairs outwards and columnar cells towards the canal between the three lobes. The stylar canal splits up into three individual arms, each leading to a locule. The epithelial cells are typical transfer cells. A composite secretion is deposited outside these cells. – The nectaries constitute three pockets between the carpels. Their secretory surface is greatly increased by folding of the epithelium and the presence of transfer cells.