While there are a number of books on identifying wild flowers, there is practically nothing on identifying plants by their fruits; yet fruits are usually on the plant much longer than flowers and are more commonly seen. To enable the reader to identify any given plant as easily as possible, from just the fruit and the leaves, Ms. Peterson has classified plants by the color of their typical fruits--red or reddish purple, black or dark purple, blue, yellow, green and white. She has then arranged the fruits within families. As a result, if you should come upon a dark purple fruit, you would simply locate its family name in the guide at the beginning of the book, and then turn to the appropriate place in the black or dark purple section. The combination of color and family makes the guide easy to use, even by the beginner. - from Amzon