Polygonum 



POLYGONACEAE 



413 



50 



Map 840 

 Polygonum natans 



f. Hartwrightii (Gray) Stanford 



~50 



Map 842 

 Dlyg^num pennsylvani'cum 



var. genuinum Fern. 



shallow water or for part of the year it may be on dry ground. The species 

 has great ability to persist even when its habitat is drained, and it often 

 advances from ditches along railroads up the banks of the fills to high 

 ground where it seems to thrive better than in a wet habitat. The habitat 

 and the vigor of the plants greatly change the character of the leaves. 

 Therefore, I believe it is useless to try to name all of the many forms. 

 Que. and Maine, to B. C, southw. to Va., La., Calif., and Mex. 



10. Polygonum pennsylvanicum L. var. genuinum Fern. (Persicaria 

 Pennsylvania (L.) Small, in part.) (Fernald. Variations of Polygonum 

 pennsylvanicum. Rhodora 19 : 70-73. 1917, and Stanford. Polygonum penn- 

 sylvanicum and related species. Rhodora 27: 173-184. 1925.) Map 842. In- 

 frequent to frequent or common in low ground along streams and road- 

 sides, in cultivated grounds, and in low grounds in general. No doubt it 

 is found throughout the state. It has been my method to collect a single 

 specimen of each species from each county. This species has been divided 

 only recently and most of my collecting was done before the division was 

 made. Since my specimens are now distributed among the three present 

 groups, the absence of records from the northern part of the state is, 

 I think, accidental. 



This species, as well as others of the genus, varies greatly in size, de- 

 pending upon habitat and date of germination of the seed. Apparently 

 the seed do not germinate under water and when they find lodgment in 

 areas which are submerged until summer, the delayed germination, no 

 doubt, accounts for the smaller plants. The largest one of which I have 

 record is my specimen no. 39887 from low ground in Gibson County which 

 I measured in the field. The height was 86 inches above the ground and 

 the longest branch was 82 inches long. 



Coastal Plain from Mass. to Miss., northw. through the Mississippi 

 Valley to Ont. and cent. N. Y. 



