Soap nuts are a natural, biodegradable and petroleum-free laundry soap alternative. They grow on trees in Nepal and India, but they're not nuts; they're actually a fruit. You might also see them sold as soapberries. The tree itself is from the genus Sapindus.Common Use: Add four or five of them, in a small cloth bag, to a load of dirty laundry. You can reuse that pouch of soap nuts for a few loads.