The floating, stoloniferous plant, Eichhornia crassipes, has high rates of productivity and rapidly invades new sites. Because the transport of carbon among connected ramets is known to increase the growth of clonal plants, we asked whether there is intraclonal carbon transport in E. crassipes. Because net photosynthesis of E. crassipes is significantly higher at high levels of atmospheric CO2, we also asked if high CO2 can change patterns of carbon transport in ways that might modify clonal growth. We exposed individual ramets within groups of connected ramets to 14CO2 for 15–45 min and measured the distribution of 14C in the group after 4 days of growth at 350, 700, 1,400, or 2,800 μ1 1−‐1 CO2. At 350 μ1 1−‐1 CO2, a parent ramet exported approximately 10% of the 14C that it assimilated to its first rooted offspring ramet. The offspring exported a similar percentage of the l4C it assimilated toward the parent; two‐thirds of this 14C was retained by the parent, and one‐third moved into new offspring of the parent. In all ramets, imported carbon moved into leaves as well as roots. At the higher levels of CO2, the percentage of assimilated carbon exported from a parent ramet to the leaf blades of its first offspring was lower by half. High CO2 had little other effect on carbon transport. E. crassipes maintains bidirectional transport of carbon between ramets even under uniform and favorable environmental conditions and when external CO2 levels are very high.