Is the apical growth of Cymodocea nodosa dependent on clonal integration?

The importance of clonal integration for the production of biomass by the apical meristem of Cymodocea nodosa (Ucria) Ascherson was tested in situ by experimental manipulation. The production of new biomass by the apical meristem of a horizontal rhizome, as well as the leaf growth of the remaining shoots, was greatly reduced when the horizontal rhizome was severed, even when up to 11 shoots were left connected to the apical meristem of the rhizome. In contrast, the elimination of up to 8 shoots after the 3 apical shoots on a horizontal rhizome did not affect the production of biomass by the apical meristem. These results show that growth at the apical meristem of a C. nodosa rhizome depends on resources translocated along the rhizome from shoots situated further than 50 cm from the rhizome apex and that all the individual shoots (ramets) in a C. nodosa clone should be considered as one unit. Clonal integration does not depend on the presence of living shoots along the translocation route but is dependent on the integrity of the horizontal rhizome.