The confidence intervals for versicolor and virginica correspond to their reported estimates of 0.93 and 1.58. That is, the offset of versicolor is estimated as 0.93 and the confidence interval spans 0.73 to 1.13. To get the estimate of the mean of versicolor, you would add the intercept to all of those numbers: a mean of 5.01 + 0.93 with the lower confidence limit at 5.01 + 0.73 and the upper confidence limit at 5.01 + 1.13.