Wood and stem anatomy of Rhabdodendraceae is consistent with placement in Caryophyllales sensu lato

Qualitative and quantitative data are given for two species of Rhabdodendro n. Newly reported for wood of the family are vestured pits in vessels and t racheids, nonbordered perforation plates, abaxial axial parenchyma, and pre sence of sphaerocrystals. Although treated variously in phylogenetic scheme s, Rhabdodendron is placed in an expanded Caryophyllales in recent cladogra ms based on molecular data. This placement is consistent with features char acteristic of most families of the order, such as nonbordered perforation p lates and successive cambia. Primitive character states in Rhabdodendron (t racheids, diffuse axial parenchyma, ray type) are shared with Caryophyllale s s.l. that branch near the base of the clade: Agdestis, Barbeuia, Simmonds ia, and Stegnosperma. Presence of vestured pits in vessels and silica bodie s in wood, features not reported elsewhere in Caryophyllales s.l., are shar ed by Rhabdodendron and Polygonaceae. Wood of Rhabdodendron has no features not found in other Caryophyllales, and is especially similar to genera reg arded as closely related to it in recent phylogenetic hypotheses. Successiv e cambia that are presumably primitive in the clade that includes Rhabdoden dron are discussed. Distinctions between sphaerocrystals and druses are off ered.