A Reinvestigation of the Development of the Embryo Sac in Gastrodia elata Blume (Orchidaceae)

The embryo sac of Gastrodia elata was reinvestigated. The ovuleis anatropous, unitegmic and tenuinucellate. The chalazal megasporeof a triad develops into an embryo sac. Four nuclei are formedat the micropylar end but only two at the chalazal end. A typicalegg apparatus and a single polar nucleus are derived from themicropylar quartet, while the chalazal two disappear beforematuration of the embryo sac. Double fertilization takes placenormally.