*4.1. Plant Materials*

The naturally occurring variegated cultivar of *Pittosporum tobira* "Variegatum" and the widely grown cultivar "Green Pittosporum" were originally collected from Pingdingshan, Henan in China and used as experimental materials. Biochemical data were recorded on three different plants of each cultivar at different dates corresponding to various temperature gradients (20–10 ◦C) from August to November (Figure 1).
