A 28-year-old woman was declared d£ad by paramedics, with her 33-year-old South African husband — who was also struck — transported to Royal Darwin Hospital.
The man remains in hospital in a stable condition, NT Health said.
NT Police Acting Commander Peter Kennon said the couple were walking past an African mahogany tree when one of its branches fell.
“There were certainly some people nearby who did witness the incident and rendered assistance immediately,” he said.
“I understand it was a confronting scene.”
He said the couple had recently arrived in Darwin, and that the South African consulate had been advised of the incident.
A house crushed by a tree in Darwin.
The botanic gardens, which is managed by Northern Territory Parks and Wildlife (NTPW), remains closed to the public.
NTPW declined to comment.
Darwin Lord Mayor Kon Vatskalis called for the removal of African mahoganies on council-managed land following Cyclone Marcus in 2018.
The cyclone caused hundreds of African mahoganies to be uprooted in Darwin, blocking roads and causing damage to cars and homes.
The NT coroner has previously found the deaths of two people in the Northern Territory caused by falling African mahogany tree branches were preventable.
Chief Minister Natasha Fyles described the incident as an “absolute tragedy”.
“My heart goes out to her family, her friends, to those that witnessed and responded to that accident,” she said.
“It has rocked our community deeply.” ABC