Is Japanese Lilac-tree Invasive?
The New York Natural Heritage Program has received two reports this year of Japanese Lilac-tree, Syringa reticulata, naturalizing in floodplains, one in Columbia County and one in Saratoga County. In Columbia County it was reported as a dominant in one area. It has opposite, heart-shaped, drooping leaves and large terminal clusters of small cream-colored flowers. It is in full bloom now and its fragrance is more like an unpleasant privet fragrance than the sweet fragrance of most lilacs. This plant has long been sold as an ornamental but its popularity may be increasing, as well as its opportunity to naturalize. It has been described on the internet as “not widely naturalizing.” If you have seen this plant naturalizing in a floodplain or any other natural area please leave a comment below. We would also like to have an idea of how widely available it is for sale in New York. Google the scientific name for more information on its natural history and horticultural use. – Steve Young
Japanese Lilac-tree in Saratoga County. Photo Jackie Donnelly
New York Flora Association Blog 
October 7, 2011 at 2:32 pm
Terrible invasive in western Mass. Japanese tree lilac has dominated the understory and mid-stratum on approximately 5-10 acres on one wooded property in Berkshire County where it has been present 30+ years. Very little else except burning bush can compete with it.
July 1, 2011 at 1:51 am
It is very invasive, but not until the seed becomes viable at about 15 – 20 years of age. It is extremely popular as a lnadscape tree. Most unfortunate.