Ellen W. Larsen & Betty I. Roots 
Flower Guide for Holiday Weekends in Eastern Canada and Northeastern U.S.A. [PDF ebook] 

A companion for visitors to the countryside on long holiday weekends who are intrigued by the flowers they see but find field guides formidable. The lively and enthusiastic text and photographs, act as a gateway for readers to deepen their interest in natural history. The book is organized into sections according to flowering times coinciding with the three North American summer holiday weekends (Victoria Day/Memorial Day; Canada Day/Independence Day; Civic Holiday/Labor Day). The flowers chosen occur widely over eastern Canada and the northeastern United States, and the majority can be spotted without even leaving the car.