With a new record out, it’s hard to believe Big Tree was once just a group of five kids struggling to decipher jazz theory at Sarah Lawrence College. The psychedelic pop band has survived the coming and going of band members, and now, with three cross-country tours behind them, has emerged as a prominent name in the indie-pop industry. To celebrate their success, Big Tree will be performing at Union Hall, in Brooklyn, on Oct. 8. The concert will showcase their original, soulful sound and complex, intricate melodies. Show starts at 8 p.m. Tickets are $8 each.