Scientific names for plants are essential. Unlike common names, which can vary widely, scientific names allow anyone in the world to know exactly which plant taxon is being referenced. However, scientific names are not set in stone and may change one or more times over the years. Taxonomists don’t make these changes on a whim–they may be based on the discovery of old records, rethinking of the importance of slight plant variations, or, ever more frequently, because scientific advancements now allow us to delve into the very DNA that defines a taxon.
Necessary as these name changes may be, I still feel a bit put out when a mellifluous name like Sophora japonica [pdf] gets changed to the far less elegant Styphnolobium japonicum. This renaming occurred because of new evidence on chromosome numbers [pdf]. But by either scientific name, this tree, commonly known as Japanese pagoda tree or Chinese scholar tree, provides some unique ornamental interest in late summer.
Growing about 40 to 60 feet tall, this species makes a handsome shade tree. Japanese pagoda tree has pinnately compound leaves with small, oval, dark green leaflets. It produces large, open panicles of small, fragrant, creamy white, pea-type flowers, much loved by bees, for weeks in August and sometimes into September. As the tiny petals fall they create a snowy blanket under the tree. The fruit of this legume family (Fabaceae) member is a pod that is constricted between each seed, making it look like a short string of beads. Japanese pagoda tree tolerates a range of conditions, including dry soils, and has been used successfully as an urban street tree. (Fun fact: Flower buds of this tree have been used to make a yellow dye–see how it and other plant-based dyes were used in ancient Japanese prints [pdf].)
Nancy Rose, editor of Arnoldia