TREE PLANTING ON STREETS AND HIGHWAYS. 41 



Observers may differ some as to the shades noted, and it must be conceded that no 

 classification can be made that will be absolutely comprehensive and correct. The 

 following schedule is submitted as tentative rather than final : 



Prevailing Colors. 



Pure Yellow. Tulip Tree, Yellow and Canoe Birches, White Maple, Yellow 

 Locust, Honey Locust, Yellow Wood, Norway and Sycamore Maples, Beech, Wil- 

 low, Cucumber, Ailanthus. 



Yelloiv Ochre. Larch, Poplar, Aspen. 



Lemon Yellow: Hickories, Black Walnut. 



Dull Yelloiv. White Elm, Chestnut, White Birch, Basswood, Butternut, Catalpa, 

 Cottonwood, Bur Oak. 



Vandyke Brown. Sycamore or Buttonwood. 



Orange. Black Birch, Horse Chestnut, Ginkgo. 



Red. Scarlet Oak, Sumach, Dogwood, Hornbeam. 



Scarlet, Crimson and Yelloiv. Red Maple. 



Red, Yelloiv and Green. Hard Maple, Sassafras. 



Scarlet, Crimson and Purple. Sour Gum. 



Purplish Red. Red Oak. 



Red and Russet. Black Oak, White Oak. 



Red, Yellow and Brozvn. Sweet Gum. 



Brozvn, Purple and Salmon. White Ash. 



Raw Umber. Scrub Oak. 



The collector of specimens will find it difficult to secure perfect leaves of a 

 straight color, ones in which the entire surface has turned to a uniform shade. 

 There is apt to be some small area of green, spots of uneven color, or defacement of 

 the surface. A careful search will occasionally reveal an unbroken leaf of pure 

 unstained yellow; but the reds almost invariably retain some of the original green, 

 or are uneven in color. 



In noting the colors assumed by various species the observer should make a close 

 distinction between ripe and dead leaves. There is both a ripening and decaying 

 process in leaves as well as fruit. The ripening stage proceeds until a separating 

 tissue or film forms between the petiole and the twig, and then, the supply of nour- 

 ishment having been cut off, the leaf dies and falls. The yellow ones soon fade or 

 turn brown after they drop ; the red ones retain their color longer, and when prop- 



