Effect of fusicoccin on the dormancy of Cercis siliquastrum seeds. The dormant scarified seeds of Cercis when treated with gibberellic acid ($GA_{3}$) show a high percentage of germination; on the contrary they react slightly when treated with fusicoccin. If increasingly larger areas of tegument are removed, the treatment with FC becomes more and more stimulating. When the removal of the tegument is complete germination takes place more rapidly in FC than in $GA_{3}$. Germination is mainly typical in $GA_{3}$ (with protrusion of radicle); it is mainly atypical in FC (with protrusion of cotyledons). These results confirm that the main dormancy factor may be located in the endosperm and point out that both $GA_{3}$ and FC may reverse the situation. The minimal effect of FC when the tegument is only scarified or partially removed may appear to be related to the low diffusion capacity of this substance which must pass through the endosperm in order to reach embryonal tissues. In fact, the germination percentage is higher if the removal takes place in the polar regions where the endosperm is thinnest.