Roots give support to a tree much as facts give support to claims and allegations. Leaves validate the health of a tree, proving its life and vitality. With neither support (roots) nor evidence (leaves), the (tree) allegation cannot stand.
(Style: spoken/casual/A=male, B=female)
A: Yamada-san no okusan, uwaki shiteru rashii yo.
B: Sonna koto, Uso yo. Mattaku ne mo ha mo nai uwasani kimatteru wa.
A: Mrs. Yamada seems to be having an affair.
B: That’s not true. That’s a groundless rumor, for sure.