Barringtonia Aquatica grows from a large seed from a tree usually found in coastal areas with warm climates. The seeds fall into the ocean and can float for years until they wash ashore and take root. Once germinated, they are an excellent houseplant or can thrive in the garden in a tropical or semi tropical climate. Here are 3 pictures of young plants and 1 picture of a more mature plant growing in our garden in Thailand.
Earlier thread. http://www.botanicalgarden.ubc.ca/forums/showthread.php?t=21304&highlight=barringtonia
Notice that they seemed to be talking about one called B. asiatica, don't know if this is a different species or a synonym - haven't looked into it.
I love this plant even only the seedling. It's quite common in tropical islands but nowhere else has this tree. I wish I can get one seed and grow it indoor in Canada.
I remember seeing this plant or something like it sold in stores for a short time many years ago. It looked like this one of Barringtonia asiatica.
If I had to make a guess it would be GardenWorks or Art Knapp. They likely got them from the local plant brokers.