Track a Lilac invites participants to find a nearby lilac and report whether they see leaves or flowers on their plant. The data contribute to a national database that will be used by researchers to better understand the timing of lilac leafing and blooming across the country.
These observations have enabled the creation of the USA-NPN's Spring Index models, which predict leafing and flowering in lilacs. These models, and associated maps, can be used to predict activity of early season plants at locations across the country and see how the timing of spring activity in a particular year compares to a long-term average.