Floral ontogeny of Pelargonium xdomesticum

Abstract

Floral ontogeny of two cultivars of Pelargonium xdomesticum L.H. Bailey, (regal pelargonium) 'Duchess' and 'Jennifer', was examined. Plants of both cultivars were grown together in a growth chamber at 15.5°C with a photosynthetic photon flux of 10 mol·m-2·d-1. Meristems were examined at 5-day intervals over an experimental period of 170 days. The initial vegetative meristem was convex with leaf primordia initiated on either side in an alternate pattern. Early floral initiation was characterized by formation of two clefts on either side of the meristem. Between the clefts new meristems developed. Proliferation of meristems continued until numerous meristems were organized in a cluster arrangement at the apex of the shoot. New meristems lacked leaf primordia and would develop into flowers. Floral organ primordia on a floral meristem were initiated in a succession of four whorls: sepals, petals, androecia, and gynoecium.