Floral ontogeny of Cneorum tricoccon L. (Rutaceae)

The floral ontogeny of the Spurge olive (Cneorum tricoccon L.) is studied by means of scanning electron microscopic observations. Special attention is paid to the sequence of initiation of the floral parts, the occurrence of septal cavities, and the development of the nectariferous tissue. The nectary disc arises as a receptacular outgrowth below the ovary and independently from stamen development. By the extensive growth of this voluminous androgynophore, stamen filaments become enclosed by nectary tissue and as a result, they are seated in pits between the lobes of the disc. Between ovary and style, three lobes are present, which are covered with stomata — their function is unknown. The significance of the unusual trimery of the flower is discussed. Floral developmental evidence supports a Rutalean affinity, although more ontogenetic investigations are needed in Rutaceae, subfamily Spathelioideae.