This mostly southern hemisphere plant family has 75 genera and 1,000 species. The flowers are usually in beautiful showy clusters and thus make them popular plants. Grevilleas and Proteas are common types. Macadamia nuts are also in this family. While these nuts are native to Australia, more than 90 percent of the world's supply comes from plantations in Hawai'i.
Systematics: The flowers are the most unusual thing about this tree. There are usually involucres bracts around the outside of the inflorescence that help give it the typical shape. There is no corolla but 4 distinct (or coalesced) calyx lobes that usually each have one stamen fixed to the end. The simple pistil is stuck between the un-opened lobes and touching the stamen. This apparently does not facility self-fertilization.
Links to more information