Shrubs, trees or herbs. Lower part of the perigone tube transforming into an anthocarp which encloses and protects the fruit; this is interpreted as a nut. One carpel. Vascular bundles in the pith frequent. Anomalous growth in thickness in all woody stems and partly also in roots with successive rings of vascular bundles. Oxalate crystals in the form of raphides. The plants are mainly tropical and mostly occur in America.

South American medicinal plants : botany, remedial properties, and general use / I. Roth, H. Lindorf. Berlin ; New York : Springer, c2002. -- p. 492.