The Joinvilleaceae are a family of flowering plants with a single genus including four species. The APG II system, of 2003 (unchanged from the APG system, 1998) assigns it to the order Poales in the clade commelinids in the monocots. The family consists of one genus with four currently accepted species, distributed from the Malay Peninsula to the Caroline Islands and high islands in the Pacific Ocean. It is evolutionarily significant as a relictual group closely related to grasses. They closely resemble large grass plants, in both general appearance and microanatomy, but possess fleshy fruits.