"Story" Mission
Keep growing upwards until...
*** Spoiler - click to reveal ***...you reach the space ship. The vine will sprout a large flower with several star seeds. Climbing down can be tricky as you need one hand to hold the seed. Seed in one hand, catch and release vine in other hand. Go down in small hops, don't try to cover a lot of ground. Even if you catch yourself you likely won't be able to hold the seed and it will plummet.