Question $9.$ Describe Figure $4$ below and discuss how these results could be linked your response in Figure $8(30$ points$)$

Figure $4.$ Average $$ standard error for leaf wall thickness $($LD$)$ of species X $($left$)$ and Y $($right$)$ grown under ambient $($white bard$)$ or elevated temperatures $($grey bars$).$ Different letters above each bar indicates a significant difference at p $<0\mathrm{.}05$ across treatments.