Plasticity of clonal integration in the perennial herb Linaria vulgaris after damage

1. Clonal integration in plants can improve their ability to cope with habitat heterogeneity. Integration may increase in response to damage, such as herbivore attack, if undamaged ramets support damaged ones. To test this, we studied the effects of apex removal and substantial defoliation on the performance of the clonal perennial herb Linaria vulgaris Mill. in a common-garden growth experiment and a C-13-labelling study. 2. In the growth experiment, contrary to expectations, the target ramet could compensate for damage better when the other ramets in the clone were also damaged, indicating within-clone competition for resources rather than support to damaged ramets. 3. In the C-13-labelling experiment, 5.7% of the label moved to a neighbour ramet in controls. Apex removal resulted in a negative net translocation of C-13 in the damaged ramet, but defoliation led to zero net translocation. 4. The observed lack of support to damaged ramets in Linaria suggests that plasticity of clonal integration in this species includes competition between sibling ramets. Although young ramets may be supported, resources are not directed towards a single damaged ramet if there are more viable intact ramets in the clone. Our main results are consistent with the notion that resource allocation among ramets depends on their relative value in terms of expected fitness profits in heterogeneous environments.