FOREWORD. 
While at the University of Wisconsin, nearly forty years 
ago, I became interested in the differences by which woody 
plants may be recognized in winter—sometimes more surely 
than when in flower—and learned from Willkomm’s excellent 
but inconveniently shaped book how readily these differences 
may be grouped for differential purposes. A large collection 
of winter twigs was accumulated subsequently at the Missouri 
Botanical Garden, and I owe a lasting debt of gratitude to 
many friends—among them the even then venerable Dr. Chap- 
man of Florida—who collected such material for me. 
Willkomm’s book, like other contemporary publications 
of its kind, was confined to the commonest deciduous trees 
and shrubs of northern Europe. My intention at that time 
was to prepare a winter manual of the trees native to the 
Eastern United States, and illustrations of many of these were 
prepared by Miss Grace E. Johnson (now Mrs. George Clifford 
Vieh). For a variety of reasons, this undertaking was laid 
aside, and her skilful and expressive drawings remain un- 
published except for those picturing Acer, Carya, Juglans and 
Leitneria. It is a pleasure to record that though long out 
of practice, Mrs. Vieh has prepared for the engraver some of 
the simplified drawings now published. 
URBANA, ILLINOIS, 
August 1918. 
