For information about how you could sponsor this page, see How You Can Help
Article from Bean's Trees and Shrubs Hardy in the British Isles
Recommended citation
'Petrophytum' from the website Trees and Shrubs Online (treesandshrubsonline.
A genus of three dwarf subshrubs in western N. America, allied to Spiraea, from which they differ in their entire, evergreen leaves and in having follicles which split down both sides.