Skyward climb
In short: A character reaches a world above by climbing a plant or taking another upward route.
Motif
How does it work in the tale?
Eigigu waters a seed and climbs its tree after it reaches the sky. Jack’s beanstalk grows overnight. The plant opens a way upward in both tales, while the time between finding the seed and climbing plays a different role.
Why does Eigigu break the branches below her?
In the Nauruan telling, Eigigu breaks the branches beneath her as she climbs towards the sky. Anyone following her would lose those footholds. While watering the seed she made a way up, and as she climbs she changes that route herself. Reaching the sky and leaving a way open for others become two separate choices.