248 



foliage, a long leaf period, and are quite free from disease and insect 

 injury. 



5. Acer saccharum Marshall. SUGAR MAPLE. SUGAR TREE. HARD 

 MAPLE. ROCK MAPLE. Plate 115. Usually large, tall trees. The 

 bark of small trees is smooth or rough, becoming fissured on old trees, 

 tight or on very old trees sometimes the ridges loosen on one edge and 

 turn outward. The leaves are extremely variable on different trees, 

 and frequently show a wide variation on the same tree, as to form and 

 in the presence or absence of hairs on the petioles and on the under 

 surface of the leaves. In our area all of the forms which have the ma- 

 jority of the leaves longer than wide or about as wide as long, may be 

 considered as falling within the type. The average sized leaves are 

 6-12 cm. long, 3-5 lobed, more or less cordate at the base, generally with 

 a broad sinus, sometimes truncate or slightly wedge-shape, sinuses 

 generally wide-angled and rounded at the base, sometimes acute, hairy 

 beneath when young, becoming smooth at maturity except for a few 

 hairs along the veins or in the main axils of the veins, or sometimes 

 remaining more or less pubescent over the whole under surface, more 

 or less glaucous beneath; flowers appear in April or May, on hairy 

 pedicels 3-7 cm. long, the staminate and pistillate in clusters on the 

 same or different trees; fruit ripening in autumn, samaras glabrous and 

 usually 2-4 cm. long. 



Distribution. Newfoundland to Georgia, west to Manitoba and 

 south to Texas. A frequent to a very common tree in all parts of Indi- 

 ana. It is confined to rich uplands, or along streams in well drained 

 alluvial soil. Throughout our area it is constantly associated with 

 the beech. It is absent in the "flats" of the southeastern part of the 

 State, and on the crest of the ridges of the "knob" area of Indiana, but 

 it is a frequent or common tree on the lower slopes of the spurs of the 

 "knobs." 



Remarks. The under surface of the leaves of the sugar maple in 

 the northern part of its range are green, while those of the southern 

 part of its range are quite glaucous beneath. To distinguish these two 

 intergrading forms the southern form has been called Acer saccharum 

 var. glaucum Sargent 1 . All of the trees seen in Indiana have leaves 

 more or less glaucous beneath. This character, however, is not 

 always evident in dried specimens. The writer prefers not to apply 

 the varietal name to the forms of our area. The sugar maple always 

 has been and will continue to be one of the most important trees of the 

 State. In its mass distribution in Indiana it ranks not less than third. 

 In the quality and uses of its wood it is equalled or exceeded only by 



iBot. Gaz. Vol. 67:233:1919. 



