If they are saying “no flowers” it generally applies to plants, too. Sometimes, the family also doesn’t want the burden – yes, it can be a burden- of caring for flowers or plants that were received because a loved one passed away. See if (and you can usually contact the funeral home) you can make a donation to a favorite charity.
When my father passed away last year, we asked for donations to a charity instead of flowers. One of my father’s friends waited about a month – he was very distraught, they knew each other for over 50 years. He wanted to do more than a donation and offered us money to cover miscellaneous expenses, we politely declined. Still searching for a way to do something for us, he sent each of us a photo that we had never seen of my father, while stationed in Germany. He was out with guys and having a wonderful time. It’s become a very cherished item of mine. Something very personal and very appreciated.
There are some wonderful suggestions above; @gailcalled has some lovely suggestions.