LATE OVULE AND EARLY EMBRYO DEVELOPMENT IN QUERCUS GAMBELII

The ovary of Quercus gambelii is tricarpellary and trilocular; each locule contains two anatropous, bitegmic ovules. The formation of a caecum from a chalazal extension of the embryo sac was observed. A central resistant column of cells, which exhibit some continuity with the vascular trace supplying the ovule, remains protruding into the embryo sac from the chalaza until the later stages of embryo development. Early embryogeny is characterized by a nearly vertical first division with both of the derivative cells contributing to the building of the embryo proper. Such observations suggest that the embryogeny of Quercus should be placed in the Piperad or Asterad type rather than the Onagrad type as has been the practice.