Fig. 2.

The three-way interaction between the explanatory factors habitat, light and seed mass on the response variable germination. Each vertical row is made up of 40 Petri dish data points for a single species (a lower number of visible data points is due to exact overlap of the germination count in some Petri dishes, and some discarded Petri dishes; see main text for details). The considerable variation in germination response within the species reflects the effects of the different temperature treatments, which are not distinguished here. The forest species show a stronger germination response in light compared with darkness, but their germination response is generally not related to the seed mass (near-horizontal lines). In contrast, the open-habitat species show a clear higher germination response with increasing seed mass (ascending lines). This effect is stronger under dark germination circumstances than in light (i.e. the lines cross).