Comparative floral structure and systematics of Pelagodoxa and Sommieria (Arecaceae)

Floral structure is compared in Pelagodoxa and Sommieria (Arecaceae, Arecoideae). Male flowers have three free, imbricate sepals, three basally congenitally united and apically valvate petals, and six stamens. Anthers are dorsifixed and dehiscence introrse. The sterile gynoecium is tricarpellate. Female flowers have three free, imbricate sepals and three free, imbricate petals, which are slightly fused with the sepals at the base. Four to six staminodes are congenitally united at the base and fused with the ovary for a short distance. The gynoecium is syncarpous. Carpels are almost equal in early development; later the gynoecium becomes pseudomonomerous. The three stigmatic branches are equally developed, apical and sessile. The carpels are (syn‐)ascidiate up to the level of the placenta and (sym‐)plicate above. Each carpel has one ovule, in the sterile carpels it is aborted at anthesis. The fertile ovule is erect up to anthesis and pendant afterwards because of the bulging out of the ovary. Pollen tube transmitting tracts (PTTT) encompass the secretory epidermis of the ventral slits of each carpel. Floral structure in Pelagodoxa and Sommieria supports the sister group relationship between the two genera suggested in recent molecular phylogenies and reflects their close relationships to a major clade of pseudomonomerous arecoid palms from the Indo‐Pacific region. © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 146 , 27–39.