''Penthorum'' is a genus of plants in the order

Saxifragales The Saxifragales (saxifrages) are an order of flowering plants (Angiosperms). They are an extremely diverse group of plants which include trees, shrubs, perennial herbs, succulent and aquatic plants. The degree of diversity in terms of vege ...

. They are erect

herbaceous perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also widel ...

s about half a meter tall. The genus consists of two species, one from east Asia and one from eastern North America. It is variously classified in the family

Saxifragaceae Saxifragaceae is a family of herbaceous perennial flowering plants, within the core eudicot order Saxifragales. The taxonomy of the family has been greatly revised and the scope much reduced in the era of molecular phylogenetic analysis. The f ...

or its own family Penthoraceae. Its closest relatives may be in

Haloragaceae Haloragaceae (the watermilfoil family) is a eudicot flowering plant family in the order Saxifragales, based on the phylogenetic APG system. In the Cronquist system, it was included in the order Haloragales. Description The Haloragaceae are ...

References

Saxifragales Saxifragales genera {{Saxifragales-stub