Fig. 4.

Volume, concentration and sugar weight of the nectar produced by male cyathia (M), male phase of hermaphrodite cyathia (H–M) and female phase of hermaphrodite cyathia (H–F) in Euphorbia boetica; sample sizes were 31, 73 and 46, respectively. Boxes represent standard errors and the bars are 1·96 s.e. Different letters indicate significant differences at a < 0·05.