26 May Fragrant Snowbell: Styrax obassia
Street tree selection is a tricky undertaking. Good candidates should be able to thrive in less than ideal conditions, (think limited growing space, ice melt, and Fido making his daily pit stop to name just a few obstacles), be of a habit that is generally upright, (no one wants a branch in the face), yet not grow large enough to tangle with utility wires or upheave walkways and paving. A candidate should ideally possess multi-season interest: flowers, showy fall color, interesting bark patterns. One such tree, seen throughout Swarthmore and found growing at the Scott Arboretum, is Styrax obassia, the fragrant snowbell.
Styrax obassia is indigenous to Japan, Korea, and Manchuria. The small-statured deciduous tree generally grows 20 to 30 feet in height. Substantial ovate leaves, dark green in color with a dense pubescence on the underside, cover the tree.
Racemes of fragrant white flowers bloom in mid-May. Despite flowering after the leaves have fully emerged, the sheer volume of flowers makes for a stunning display. Each flower raceme is composed of several dozen individual pendant fragrant white flowers. Another, albeit fleeting, display occurs when individual flowers fall and blanket the ground.
Fertilized flowers give way to small ¾” drupes. Leaves transition to golden yellow in the autumn. Bark is smooth and becomes slightly furrowed along the trunk with age.
Fragrant snowbell is best suited to full sun and partial shade locations. Trees grow, but flowering is reduced if planted in dense shade. Transplanting is most successful with small trees planted in spring. While S. obassia has shown great promise as a street tree throughout Swarthmore, care should be given to appropriately prepare the planting site. A well-dug, well-aerated and amended soil will help ensure success.
While suitable for street tree situations, Styrax obassia would be an ideal candidate for any small scale space or as an understory tree. Three accessions are currently growing at the Scott Arboretum. Numerous trees can also be seen along Cedar Lane and Ogden Avenue.