6 JOURNAL OF THE ARNOLD ARBORETUM [vol. i 



21, 1. 11 (1829). — ?5. amhigua Pursh, Fl. Am. Sept. 617 (1814). — ?S. Pursh- 

 iana Sprcngel, Syst. V. 608, in indice (1838). — S. nigra var.falcata Torrey, 

 Fl. N.Y. II. 209 (1843). — Carey in Gray, Man. 429 (1848). — Andersson 

 in Ofv. Svensk. Vetensk. Akad. Fcirh. xv. 114 (1858). — Newhall, Trees 

 N.E. Am. 74, fig. 37 (1890). — Sargent, Silva N. Am. ix. 104, t. 463 (1896).— 

 S. nigra a, angustifolia a. falcata et /3. longifolia Andersson in Svensk. 

 Vetensk. Akad. Handk vi. 20 (1868). — S. nigra b, latifolia a. brevijidis et 

 /3. longijuUs gracilescens Andersson, 1. c. 21 (1808). — S. nigra [subspec.] 

 S. furcipila Gandoger, Fl. Europ, xxi. 167 (1890). — S. nigra [subspec.] 

 S. leptodes Gandoger, 1. c. — S. nigra [subspec.j S. ventricosa Gandoger, 1. c. 

 A very well-known eastern species the range of which seems to extend 

 along the Atlantic coast from southern New Brunswick to northern North 

 Carolina, and westward through northwestern South Carolina and northern 

 Georgia (from where I have not yet seen typical material) to central and 

 eastern Alabama (probably also to northern Missouri), southern Arkansas 

 (where var. altissima is the prevailing form) and from northern Louisiana 

 to northeastern Texas (where it seems to spread in the central parts as 

 far south as Val Verde County on the Rio Grande, although most of the 

 material from Texas belongs to var. Lindheimerii), The southern borderline 

 of the range of S. nigra reaches its most western }x>int at about lOO'' W. L., 

 and from there runs northward through central Oklahoma and the eastern 

 parts of Kansas, Nebraska, and South Dakota.^ For the northern limit 

 of its range may be taken a line running from about the 95th degree W, L. 

 along the north shores of Lake Superior through southern Ontario and 

 Quebec to southern New Brunswick. 8. nigra does not occur in the south- 

 west or west where it is represented by S. Gooddingii. In the south the 

 typical form apparently passes by many intermediates into var. Lind- 

 heimcrii and var, aliissima. Of peculiar interest are the forms of the south- 

 east from Virginia to northern Florida because they show a smaller number 

 of stomata on the upper surface of the leaves. ^Yllile in the typical form 

 as well as in var. altissima and var. Lindheimcrii the number of the stomata 

 is scarcely less on the upper than on the lower leaf-surface, these south- 

 eastern forms sometimes only have a few stomata along the midrib and 

 even these seem to be occasionally wanting. I have not yet been able to 

 detect other characters to separate these forms from typical nigra but for 

 two reasons I think it best to enumerate them below. Firstly, they cer- 

 tainly need a further study, and secondly I wish to draw the special at- 

 tention of all collectors to them, because the distribution of S. nigra in 

 the southeast is very insuflSciently known, and material of it from that 



1 According to the map given by Hough S. nigra inhabits almost the whole state of Kansas^ 

 the eastern half of Nebraska and South Dakota, the southeastern corner of North Dakota and 

 nearly the whole of Minnesota except the northwestern corner. I have not yet seen material 

 from the Dakotas and Minnesota but according to Lunell's enumeration (Am. Midi. Nat. 

 IV. 197 [1916]) S. nigra is wanting in North Dakota, and according to Petersen (Fl. Nebr. ed. 

 2, 09 [1912]) it occurs in Nebraska only in the eastern part of the state. It is absent from 



northern central and western Kansas (see Hitchcock in The Industrialist, xxrv. 323 [Fl, 



Kansas] [1899.]) 



