SPUR. A dwarf branch, sometimes modified to form a spine. Since 

 the dwarf branch grows little in length, such leaves or leaf-scars as 

 it bears are crowded and their arrangement is difficult to make out. 

 Reference should be made to a young, rapidly growing twig. 



STALKED BUD. A bud raised above the twig on a Httle stem. Since 

 only one leaf or leaf-scar is found it is distinguished from a spur. 



STEM. Includes trunk, branches and twigs. Most winter-buds develop 

 into twigs and so are embryo stems. 



STIPULES. The more or less leafy outgrowths at the base of a leaf. 

 Sometimes there are none, sometimes they drop ofT very early and 

 leave a scar, sometimes they are attached to the petiole and so leave 

 no trace after it drops, sometimes they are seen as spines, and often 

 they form scales of winter-buds. 



STIPULE-SCARS. The tiny, more or less horizontal marks often 

 found at each side of the leaf-scar after the stipules have dropped 

 off. If the stipules were very large the scars may meet around the 

 twig, forming a ring. Sometimes they are unequal in size. 



SUPERPOSED BUDS. Two or more buds arranged one over another. 



SURFACE. The outside of a leaf or other part of a tree. 



TIP. The outer end of the leaf or twig; the part farthest from the 

 stem. The opposite of BASE. 



TOOTHED. A margin cut into points. As used here it implies single 

 points (see DOUBLE-TOOTHED). Not mdented deeply enough 

 to make lobes. 



TREE. Here considered to be a woody plant at least 13 ft. (4 meters) 

 high, having one main trunk, which branches into others at a per- 

 ceptible distance from the ground. Plants which are ordinarily 

 shrubs are included in the KEY if they have these characteristics. 



TRUNK. The lower part of a tree before it breaks up into branches. 

 Sometimes it runs through the tree, giving off branches on the 

 sides. 



TWICE COMPOUND. See BIPINNATELY COMPOUND. 



TWIG. Here applied to the most recent growth of the stem, the end 

 of a branch, unless qualified by such a word as "older." It is mark- 

 ed at the outer end by a winter-bud or by its own tip, and at the 

 inner end by a series of encircling rings which are the remains of 

 the winter-bud which gave rise to it. 



UNARMED. Without spines or prickles. 



UNDER. The direction towards the bottom or the inside of the tree. 



UPPER. The direction towards the top or the outside of the tree. 



USUALLY. Implies "not always." Indicates that there is at least one 

 species which does not agree with the description. 



VARIETIES. Sub-divisions of species, differing only slightly and un- 

 essentially from well-marked species. They are not included in this 



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