The palms that were laid on the drive to Jerusalem; Palm Sunday, are collected, kept all year, and then burned the following year, for the ashes of Ash Wednesday, that begins the new Easter Season. Then new palm bows are gathered, for this Palm Sunday.
You know, it's funny - during my brief childhood years as a Catholic, Palm Sunday was always one of my favorites, if not the favorite service of the year. When I think about this in hindsight, that service in particular is the most Pagan of them all and it definitely foreshadowed my attraction to and destiny as a contemporary Pagan. It was one of the few services that was more participatory - and participatory ritual is sort of the bread 'n butter of Paganism - plus I got to take home a cool plant part. Loved that it included plants. We would sometimes make them into strips and weave or braid them once we got home to hang around the house.