system
Given the following post, respond as if you're commenting on Reddit:
human
Why only some plant cuttings grow when put in water?

There are some plants that will happily grow roots and be perfectly happy when put in just water, like  some vines. Put just a bare section from a willow tree in a jar of water and it will grow roots and a new shoot of leaves from the top. But a branch taken from a birch will first grow leaves but then start to wilt within a week.

Why don't all plants or trees be like willows?
gpt
Well pretty much any plant can grow roots in water, it's just that plants that aren't woody grow them much easier and faster. Most woody cuttings need some rooting hormone to help them grow roots in water, but it's still possible. Willow contains lots of indolbutyric acid (which is an auxin) and salicylic acid which both help in growing roots. Some people use willow extract to help other cuttings root as well.