678 The Trees of Great Britain and Ireland 



Varieties 



The sugar maple is very variable in the wild state, and certain varieties of it 

 are now recognised as distinct species by Sargent in his latest book on American 

 trees. Two of these Acer floridanutn, Pax, a moderate-sized tree, growing in the 

 Southern States and in Texas and Mexico, and Acer leucoderme, Small, a low tree 

 ranging from North Carolina to Arkansas would probably not be hardy if 

 introduced, and need not be further mentioned by us. Acer nigrum, Michaux, 

 now considered by Sargent to be a distinct species, is best treated as a variety of 

 A. saccharum, and is to be carefully distinguished from var, Rugelii, with which it 

 has been confused. 



1. Var. nigrum, Britton, Trans. N.Y. Acad. Set. ix. 10 (1889). 



Acer nigrum, Michaux f. Hist. Arb. Am. ii. 238, t. 16 (i 810); Sargent, Garden and Forest, 

 1891, p. 148, f. 27, and Trees JV. Amer. 634 (1905). 



Leaves green beneath, cordate at the base, with the basal sinus closed by the 

 approximation or overlapping of the lobes ; sides of the blade drooping ; lobes 

 usually three, occasionally five ; acute, entire or obtusely toothed. Bark of old 

 trees deeply furrowed, sometimes almost black. Young branchlets orange-coloured. 



This variety, according to Sargent, is widely distributed, extending from 

 Ontario and the valley of the St. Lawrence, near Montreal, southward to Virginia 

 and Kentucky, and westward through Michigan, Indiana, Illinois, Iowa, and 

 Missouri to South Dakota and Kansas. It is comparatively rare near Montreal 

 and Vermont, becoming more abundant farther west, almost replacing the type in 

 Iowa, and the only form in South Dakota. It was first noticed by the younger 

 Michaux on the banks of the Genesee River in New York, where it still forms a 

 forest of considerable size. 



Loudon states that the black sugar maple was introduced in 181 2 ; but it is 

 now very rare in cultivation. Var. monumentale, Temple, a tree of upright 

 columnar habit, occasionally seen in botanic gardens, is a form of var. nigrum. 



2. Var. Rugelii, Rehder, in Sargent, Trees N. Amer. 633 (1905). 



Acer barbatum, Michaux, PI. Bor. Am. ii. 252 (1803). 



Acer barbatum, var. nigrum, Sargent, Silva N. Amer. ii. 99, t. 91 (1892). 



Acer Rugelii, Pax, in Engler, Bot. Jahrb. vii. 243 (1886). 



Leaves pale beneath, papery in texture, three-lobed, entire or with short obtuse 

 teeth. This is the common and frequently the only form of the sugar maple in the 

 region from North Carolina and Georgia to Missouri ; and is occasionally met with 

 as far north as Michigan and Prince Edward's Island, leaves of this form sometimes 

 appearing on the upper branches of trees, which bear on their lower branches 

 typical leaves of the ordinary form of the species. This variety does not appear to 

 be in cultivation in England. (A. H.) 



