Not many artists get the chance to ask themselves how to make their 153rd album feel special. But not many artists are Willie Nelson. Still a workhorse into his nineties, the beloved country icon has been going at a pace of about two studio records a year for some time, owing to his partnership with producer Buddy Cannon, who’s worked out a plug-and-play system to keep Nelson and his trusty longtime companion, nylon-stringed 1969 Martin guitar Trigger, recording covers and the occasional original at a clip of as many as 14 in a single day. While efficient, this hasn’t always allowed for a lot of spontaneity or variety, so when Nelson’s manager wanted to try shaking things up, he didn’t have to look far for a new collaborator: Nelson’s son Micah, who records as Particle Kid. “I was flooded with a million different emotions all at once, and my imagination was having a field day with all the possibilities, all the directions it could take,” Micah tells Apple Music. “How can I blend my more sort of impressionistic DIY approach to music with his own ethos and style and aesthetic and his history? How can we merge all those things in a way that feels natural and authentic?” The initial idea was an album of Tom Waits covers, but as Micah revisited Willie’s albums Spirit and Teatro, from 1996 and 1998, respectively, he landed on an approach that became Last Leaf on the Tree. “One thing I felt wasn’t showcased enough on a lot of the records that my dad had been making was silence and space and room for Trigger and him,” Micah says. “So Spirit came to mind, which is one that I always loved as a kid. There’s four things happening in the whole album—there’s no bass, there’s no drums. It’s my dad, Aunt Bobbie on piano, Johnny Gimble on a fiddle and Waylon Payne on his guitar. And you don’t miss anything. It’s such an emotionally potent record, and you can hear everything going on—it’s like you hear the soul of the people playing. It’s a very slippery slope with music—there can be so much sound that you can’t hear anything.” With this in mind, he cast a wider net, presenting for his father a more eclectic selection of songs to work with. Some, like Waits’ “Last Leaf” and “House Where Nobody Lives”, and particularly Warren Zevon’s final transmission “Keep Me in Your Heart”, are by contemporaries of Willie’s, facing the spectre of death head-on. But Micah also included more recent artists like The Flaming Lips, whose elegiac “Do You Realize??” has a different urgency in this context. “I didn’t sit down and go, ‘I want this album to be about death and love,’” says Micah. “I grew up loving The Flaming Lips. That song came to my head, and when I imagined my dad singing, it had a whole new weight to it, knowing his whole life history and how many of his friends are gone.” The sparse arrangements keep the focus on Willie’s distinctive, sometimes unsteady delivery. “You can hear the detail of my dad’s voice at his age, and every lyrical phrase of Trigger,” says Micah. “All of those things are part of the composition, part of the painting.” Willie’s takes on lovelorn ballads like Beck’s “Lost Cause” or Keith Richards’ “Robbed Blind” don’t feel like they’re about a relationship—they feel like they’re about all the relationships. “I look at those and I go, ‘Oh, these are country songs, and this is something my dad’s experienced on more than one occasion, so he can relate to this and sing it honestly.’ With a song like ‘Lost Cause’, a 20-year-old singing that is one thing; a 92-year-old singing it and suddenly it becomes far more existential.” For Micah, the album’s highlight isn’t any of its revelatory covers, but rather the one song he and his father wrote together, “Color of Sound”. “All these reinterpretations were really great, but I wanted to have at least one song on there he wrote himself that was current. We were sitting on the bus, and I asked him if he’d written anything new, if he had any new songs, and he said, ‘No, I wrote them all.’ Then he said, ‘Well, I got this one thing: If silence is golden, what color is sound?’ To me, that was where I felt like, ‘OK, now this is our record. We have this song we wrote together.’” If Last Leaf on the Tree were to be Willie Nelson’s final album—and there’s no reason to assume it will be—it would be a fitting and definitive capstone on a singular American life and career. But for Micah Nelson, it’s that and so much more. “Honestly, I’m just grateful that he’s lived long enough to be able to make this record with me, that he’s this healthy at this age and has this much spunk left,” he says. “It’s profoundly meaningful. Also, just the understanding that I might not ever get another chance to make a record with him, so this has to say something.”