Abstract: Various growth reactions were observed following different kinds of longitudinal splits in the radicles of the excised mature embryos or in the young roots (5–10 mm in length) of the intact embryos with female gametophytes in Pinus koraiensis Sieb. et Zucc. If a shallow incision was made in the radicle of the excised embryo and groups of the initial cells were so equally divided in halves, a root primordium originated normally from cach half. However, they became small and abnormal roots and eventually ceased to grow. If a deep incision was cut through the groups of the initial cells extending towards the differentiated tissues, the incised portions split apart and subsequently recurred following 2–3 weeks culture. At this time the apical meristem quickly transformed to mature parenchyma and ceased to extend any further. It appeared to be that the more mature tissues as well as the apical initial cell groups would also affect the root development after the incision. With intact female gametophyte the initiation and growth of the roots were normal, however, following either shallow or deep incision of the radicle of the germinated embryo. It is therefore suggested that the female gametophyte of the pine seed is essential both as a nutritional source for germination and a regenerative factor of the radicle.