We have two of them in the Garden, and this post is about the one in Area F (the other grows in Q, along the W path; + one styrax obassia, also native to Japan, which grows in W). S. japonicum in F is best viewed form across the lawn at the south end of the Area F for its outline and growth pattern, and from the second shortcut for an up-close inspection. Styrax japonicum blooms beginning of June, usually a week+ later than styrax obassia. This year s. japonicum started to bloom about the time when s. obassia started to drop its flowers.
From Wikipedia, general info on styrax: Styrax is a genus of about 130 species of large shrubs or small trees in the family Styracaceae, mostly native to warm temperate to tropical regions of the Northern Hemisphere, with the majority in eastern and southeastern Asia, but also crossing the equator in South America. Common names include styrax, or the more ambiguous storax, snowbell, and benzoin. […]
From Missouri Botanical Garden: […] Japanese snowbell is a compact, deciduous flowering tree with horizontal branching and a rounded crown. It typically grows to 20-30’ tall and as wide, but infrequently can reach up to 50’ tall. It is noted for its pendulous clusters of bell-shaped, mildly fragrant, 5-petaled, waxy white flowers (each to 3/4” diameter) that bloom in May-June. Drooping flower clusters are easily visible because of the upward posture of the foliage. Flowers give way to greenish-brown, olive-shaped drupes that often persist into late autumn. […]
Here is link to Peter Meyer’s article ‘The snowbells of Korea’ – it’s about both s. japonicus an obassia; Harvard University posted it in PDF form, so it doesn’t copy, but you can go there and enjoy reading it.