The late botanist Bill Greiner introduced me to the Bronx River Pathway,

a wonderful area for spring ephemerals. It is a narrow strip running

along the river between the Bronx River Parkway and the Metro North railroad.

According to Bill the best time to see the flowers is between April 17-23,

weather dependent. The flowers are found along a mostly paved path

between Crestwood & Scarsdale, NY.

http://parks.westchestergov.com/index.php?option=com_content&task=view&id=1900&Itemid=4466

http://www.westchestergov.com/Parks/pdfs/Maps/BronxRiverPathway.pdf