TIMING OF EMBRYO ABORTION AND THE EFFECT OF OVULE THINNING ON NUTLET MASS IN CRYPTANTHA-FLAVA (BORAGINACEAE)

Just after a size difference was apparent among the four single-ovulate subunits in developing ovaries of Cryptantha flava (Boraginaceae), either the largest subunit or the three smaller were destroyed and final seed set and nutlet mass were scored. Results indicate that most irreversible embryo abortion must occur during the establishment of the size differences, and within a 24-48 h period. Thinning a portion of the ovules does not affect final nutlet mass. © 1990 Annals of Botany Company.