All these families belong to the orders Cucurbitales , Fagales , and Rosales , which together with the Fabales form a clade of eurosids .
Although most plants able to form nitrogen-fixing root nodules are in the legume family Fabaceae , there are a few exceptions : All these families belong to the orders Cucurbitales , Fagales , and Rosales , which together with the Fabales form a clade .