w es ▁as ▁" similar ▁in ▁habit ▁and ▁fol i age " ▁( see ▁' External ▁links ') ▁and ▁ ▁tall ▁by ▁▁ ▁in ▁g irth ▁in ▁ 1 9 1 2 , ▁was ▁confirmed ▁by ▁Helen ▁B anc ro ft ▁in ▁a ▁Gard ener ' s ▁Chron icle ▁article ▁in ▁ 1 9 3 4 ▁as ▁a ▁' V eg eta '- type ▁hy brid ; ▁it ▁was ▁propag ated ▁by ▁Hey bro ek ▁in ▁ 1 9 5 8 ▁and ▁cultiv ated ▁at ▁the ▁Ba arn ▁el m ▁research ▁inst itute ▁as ▁clone ▁P 4 1 . ▁The ▁tree ▁surv ived ▁till ▁the ▁ 1 9 6 0 s . ▁Like ▁the ▁Queens ' ▁College ▁Ch ich ester ▁el ms ▁in ▁Cambridge , ▁the ▁Mag d alen ▁College ▁trees ▁were ▁not ▁observed ▁to ▁produce ▁root ▁su ck ers , ▁though ▁The ▁Gro ve ▁at ▁Mag d alen ▁has ▁long ▁been ▁a ▁de er ▁park , ▁and ▁any ▁su cker ▁growth ▁is ▁likely ▁to ▁have ▁been ▁cro pped . ▁The ▁Oxford ▁zo ologist ▁Robert ▁Gun ther ▁attributed ▁the ▁larger ▁tree ' s ▁unusual ▁size ▁to ▁the ▁fact ▁( dis cover ed ▁in ▁ 1 9 2 6 ) ▁that ▁it ▁had ▁been ▁growing ▁on ▁a ▁ph osph ate - rich ▁b one - bed , ▁made ▁up ▁of ▁the ▁remains ▁of ▁m amm oth s ▁and ▁other ▁pre histor ic ▁animals . ▁ ▁With ▁a ▁g irth ▁of ▁ 6 . 9   m ▁( 2 2 . 6   ft )