Ovule and megagametophyte development is described for the first time in Ecdeiocoleaceae, a small Western Australian family that has affinities with Restionaceae. The mature embryo sac has an egg apparatus, but other nuclei usually degenerate. The nucellus proliferates at the chalazal end of the embryo sac to forma prominent cup-shaped region that has no obvious homologue among related families in Poales, or tother monocotyledons. The data confirm evidence from anatomy and pollen morphology that Ecdeiocolea does not belong in Restionaceae, but do not indicate obvious relationships with other families.