444 BiCKNELL : Ferns and flowering plants of Nantucket 



This plant seems to have been little recognized in our flora 

 and very imperfectly understood. A detailed description may 

 therefore be of service : 



Pale glaucescent green, relatively stout, usually rather low, 

 erect or ascending with mostly short branches, the main inter- 

 nodes often 2-5 cm. long, conspicuously striate, usually hollow 

 with firm often thin walls ; leaves commonly rather thin, rela- 

 tively broad, elliptic to obovate- oblong, sometimes narrower, the 

 main stem-leaves narrowed to distinct, even slender, petioles, 

 rather abruptly acute or acutish or the upper ones obtuse, 2-6 

 cm, long, 0.5-2 cm. wide, smaller, narrower, and crowded towards 

 the ends of the branches, prominently veined beneath, the margins 

 distinctly crisped ; ochreae conspicuous, silvery white, often 

 purplish at base, becoming pale brown, narrowly acute, finally 

 lacerate into weak divisions; flowers clustered in the axils, often 

 distinctly pedicelled, rather large, at maturity mostly 3-3.5 mm. 

 long, green with strongly contrasting white margins, rarely 

 slightly ptirplish-tinged ; achene broadly trigonous-ovoid with 

 concave faces, commonly 3 mm. long by 2 mm. thick, rather 

 acute, dark, dull, finely rugulose-striate. 



A shorter, stiffer, and usually stouter, plant than Polygonum 

 avicidare, paler green, with broader, more venose and crisped leaves, 

 usually more crowded on the fewer and shorter branches, larger and 

 more conspicuous ochreae, larger flowers, commonly wjth little or no 

 purplish tinge and larger, broader, more sharply trigonous achenes 

 with the faces more concave. 



Large forms are sometimes mistaken for Polygonum erectwn 

 L., which differs materially in its distinctive yellowish green color, 

 solid woody stem of shorter internodes, less whitened ochreae, 

 more dilated and often somewhat crested angles of the mature 

 calyx and broader, less dark-colored achene ; it is also later- 

 flowering, often by several weeks. 



Note, — Polygonum erecium'L,, is said in Mrs. Owen's catalogue 

 to be found occasionally on the wharves. It may well have 

 occurred, but I could find nothing of it, and the species was formerly 

 so poorly understood that Polygonum monspeliense might easily 

 have been mistaken for it. 



* Polygonum buxiforme Small, Bull. Torrey Club 33 : 56. 1906. 



P. littorale Small, in part. Mem. Dept. Bot. Columbia Coll. 

 I: 102. 1895. Not /I ////i7r^/^ Link. 



