▁they ▁will ▁not ▁germ inate ▁well ▁in ▁the ▁aut umn . ▁Of ▁all ▁the ▁factors ▁affect ing ▁the ▁germ ination ▁of ▁Dra ba ▁v erna , ▁light ▁is ▁the ▁lowest ▁influen cer . ▁ ▁Ph y log eny ▁Studies ▁performed ▁have ▁tried ▁to ▁map ▁the ▁evolution ary ▁history ▁of ▁the ▁genus ▁Dra ba , ▁with ▁D . ▁v erna ▁included . ▁Due ▁to ▁certain ▁unique ▁tra its ▁that ▁D . ▁v erna ▁possess ▁it ▁is ▁believed ▁that ▁this ▁species ▁is ▁a ▁very ▁ancest ral ▁species ▁in ▁the ▁genus ▁Dra ba , ▁referred ▁to ▁as ▁one ▁of ▁the ▁Core ▁Dra ba . ▁It ▁has ▁been ▁found ▁to ▁have ▁a ▁very ▁highly ▁variable ▁number ▁of ▁chrom os om es , ▁ 2 n = 1 4 , ▁ 2 8 , ▁ 3 0 , ▁ 3 2 , ▁ 3 6 , ▁ 3 8 , ▁ 3 9 , ▁ 5 2 , ▁ 5 8 ▁to ▁ 6 4 ▁pairs ▁of ▁chrom os om es . ▁The ▁base ▁chrom os ome ▁number ▁has ▁not ▁been ▁determined ▁yet , ▁giving ▁proof ▁that ▁this ▁species ▁has ▁a ▁complex ▁evolution ary ▁past ▁in ▁order ▁to ▁become ▁as ▁w ides p read ▁as ▁it ▁is . ▁It ▁is ▁the ▁only ▁species ▁in ▁the ▁genus ▁Dra ba ▁that ▁is ▁natural ized ▁world wide . ▁It ▁is ▁hypoth es ized ▁that ▁one ▁of ▁the ▁causes ▁of ▁the ▁variable ▁pol yp lo id y ▁in ▁this ▁genus ▁us ▁due ▁to ▁the ▁P li oc ene ▁and ▁Ple ist oc