na-adjective
heavily laden (of a branch); sagging; drooping; bent low
Describes branches or plants bending under the weight of fruit, flowers, or snow. Often used in the set phrase たわわに実る (to bear fruit in abundance).
柿の木がたわわに実をつけている。
The persimmon tree is heavily laden with fruit.
桜の枝が花でたわわにしなっていた。
The cherry branches were drooping under the weight of blossoms.
The origin is uncertain. It may be related to the verb たわむ (to bend), but the exact derivation is unclear.