Differential seed set in proximal and distal fruit segments of Cakile edentula var. edentula.

Abstract

Buds, flowers, and young fruits from a Lake Michigan population of Cakile edentula var. edentula were studied to determine if differential ovule production and pollen tube growth in proximal and distal fruit segments can explain the significantly lower seed set in the proximal fruit segment. Ovule production was significantly higher in the proximal fruit segment; therefore, ovule number could not be found to limit proximal seed set. Likewise, pollen tubes were numerous and appeared equally distributed between the segment types. Maternal resources and a selection for the well-dispersed distal fruit segment with an easily germinable seed were speculated as factors causing differential seed set. The occurrence of females (males-steriles) in this population of a normally hermaphroditic species is also noteworthy.