Pterostemonaceae Small

John Kunkel Small

John Kunkel Small was an American botanist.He was the first Curator of Museums at The New York Botanical Garden, a post in which he served from 1898 until 1906. From 1906 to 1934 he was Head Curator and then from 1934 until his death he was Chief Research Associate and Curator...

 is a small family of shrub

Shrub

A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...

s native to tropical and subtropical Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

. The family was recognized by scientists working with the Angiosperm Phylogeny Group but is placed in the Grossulariaceae by other taxonomic systems. The APG III system

APG III system

The APG III system of flowering plant classification is the third version of a modern, mostly molecular-based, system of plant taxonomy...

 of 2009, however, does not recognize this family and places it within the Iteaceae

Iteaceae

Iteaceae is a flowering plant family of trees and shrubs native to the eastern USA, south eastern Africa, and south and Southeastern Asia. Some older taxonomic systems place the genera in this family in the Grossulariaceae. The APG III system of 2009 includes the former Pterostemonaceae in Iteaceae...

 in the order Saxifragales

Saxifragales

Saxifragales is an order of flowering plants. Their closest relatives are a large eudicot group known as the rosids by the definition of rosids given in the APG II classification system. Some authors define the rosids more widely, including Saxifragales as their most basal group. Saxifragales is...

.