How do tree branches form? © Getty Images

How do tree branches form?

Trees can branch out with a little help from buds, the growth hormone auxin, and their apical meristem...

Asked by: James Slatter, Feltwell


As tree trunks grow upwards, buds are produced on either side. These buds are initially dormant because the growing tip at the top, called the ‘apical meristem’, produces the hormone auxin, which inhibits their development. Once the apical meristem has grown far enough away, the concentration of auxin near the bud drops and it can begin growing sideways. This sideways shoot also lays down its own buds, which are in turn kept dormant until the shoot’s own growing tip has advanced enough.


Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.