(556 



ACERACEAE 



Acer 



o ~^o 

 Map 1364 



Acer sacchannum L. 



50 



Map 1365 



Acer rubrum L. 



50 



Map 1366 



Acer nigrum Michx. f. 



northern Indiana it is found both on gravelly ridges and in low ground, 

 and rarely in bogs. In southern Indiana it is an infrequent tree on 

 the ridges in most upland woods where it is associated with white oak, 

 and in the "flats" in low, wet woods it may be frequent and is associated 

 with sweet gum and beech. In the "flats" it grows to a large size and repro- 

 duces abundantly in wet, fallow fields. 



Newf. to Minn., southw. to Fla. and Tex. 



3a. Acer rubrum var. Drummondii (Hooker & Arnott) T. & G. I have 

 this variety from only the cypress swamp in Knox County and from 

 swampy woods in the southern part of Posey County. 



In deep swamps from sw. Ind., down the Mississippi Valley to La. and 

 westw. to e. Tex. 



4. Acer nigrum Michx. f. Black Maple. Map 1366. Throughout the 

 state and always associated with the sugar maple. Almost pure stands of 

 the sugar maple, however, may occur with this species absent. When 

 the two are associated, the black maple will usually be found in the 

 moister area. Usually infrequent but locally common. I have seen speci- 

 mens of this form with the glabrous petiole from the following states: 

 Que., Maine, Vt, Mass., N. Y., Del., Va., W. Va., S. C, Ky., Tenn., Ohio, 

 Mich., Ind., 111., Wis., Minn., Iowa, and Mo. 



4a. Acer nigrum Michx. f. forma pubescens Deam, f. nov. A forma 

 typica recedit petiolis pubescentibus. Petioles more or less pubescent 

 their entire length. This form is associated with the species throughout 

 the state but is less frequent than the glabrous form. Type in Deam Her- 

 barium no. 58539, Randolph County, Sept. 30, 1937. I have seen specimens 

 from the following states : Que., Ont., Vt., N. H., N. Y., W. Va., Ind., 111., 

 Wis., and Mo. (Atherton). 



4b. Acer nigrum var. Palmeri Sarg. (Jour. Arnold Arb. 2: 166. 1921.) 

 This is a form with leaves 3-lobed and is far more common than the 

 species in the northern part of the state. 



