Apical Events Prior to Floral Evocation in Cyclamen persicum 'F-1 Rosemunde' (Primulaceae)

Abstract

The shoot apex of Cyclamen persicum `F-1 Rosemunde' (Primulaceae) was examined by dissection and light microscopy to determine changes prior to floral evocation. Many morphogenetic changes associated with floral induction in daylength-sensitive plants also occur in this day-neutral Cyclamen cultivar. The shoot apex is initially located on the flank of the single cotyledon. Apical orientation is shifted by differential growth of the bases of leaf 1 and the cotyledon, which may also effect a shift in phyllotaxy. The size of the apex and the activity of the apical meristem increase at least through the first 20 wk of growth. The number of tunica layers increases, and a pattern of cytohistological zonation appears. During the early months of growth, the rate of leaf initiation and the number of unemerged leaves increase. A time frame of apical events is presented to guide future studies on the promotion of flowering in Cyclamen.