ipig] SARGENT— NORTH AMERICAN TREES 233 



Acer saccharum Marsh.— The lower surface of the leaves of 

 the northern sugar maple is usually green and glabrous, but it is 

 sometimes glaucous or glaucescent and southward is slightly pubes- 

 cent along the under side of the midribs and veins; and as the pale 

 color of the lower surface of the leaves gives the trees a distinct 

 appearance the varietal name adopted for them by some European 

 dendrologists will probably be helpful. This form becomes 



Acer saccharum var. glaucum, nov. comb. — A. saccharinum 

 var. glaucum Pax, Engler Bot. Jahrb. 7:242. 1886; Wesmael in 

 Bull. Soc. Bot. Belg. 29:61. 1890. — A. palmifolium var. glaucum 

 Schwerin, Gartenflora 42:455. 1893. — The leaves of this variety 

 resemble those of the green-leaved variety in size and shape and 

 are glabrous or in the southern states usually slightly pubescent on 

 the under side of the midribs and veins. 



From the North, where it is much less common than the green-leaved form, 

 I have seen specimens of this variety only from Isle-aux-Couvres in the St. 

 Lawrence River, from Prince Edward Island, Nova Scotia, Lake St. John and 

 St. Anne's, Quebec, northern V'ermont, Cooperstown, New York, western 

 Pennsylvania, and Youngstown, Ohio; it is more common in southern Michigan 

 and Indiana, and occurs in northeastern Iowa and central Tennessee. It is 

 still more common in Missouri and northern Arkansas, and is the only form I 

 have seen from South Carolina, Alabama, Mississippi, Louisiana, and southern 

 Arkansas, where the sugar maple is not a common tree. 



Acer saccharum var. Rugelii Rehder, Cyclopedia Am. Hort. 

 1:13. 1900; Sargent, Man. /g. 5/5. 1905. — ^ . i^wge/ii Pax, Engler 

 Bot. Jahrb. 7:243. 1886. — A. saccharinum subspec. Rugelii Wes- 

 mael, Bull. Soc. Bot. Belg. 29:61. 1890. — In The Silva of North 

 America this form of the sugar maple was confused, at least in part, 

 with A . nigrum. As it is now understood, the leaves of this variety 

 are usually broader than long and are cordate or rounded at base, 

 3-lobed with long acuminate lobes, usually entire or the lower lobes 

 occasionally furnished near the base with a small rounded lobe ; the 

 leaves are -3-nerved, thick, dark green above, green or glaucescent 

 and glabrous on the lower surface, but on specimens collected by 

 Palmer at Williamsville, Wayne County, Missouri (no. 6096), and 

 from a large tree with short-lobed leaves at Campbell, Dunklin 

 County, Missouri (C. S. Sargent, October 5, 1910), the lower surface 

 of the leaves is thickly covered with loose pubescence. 



