IRbofcora 



JOURNAL OF 



THE NEW ENGLAND BOTANICAL CLUB 



VoL 4 April, 1902 



No. 40 



THE NEW ENGLAND POLYGONUMS OF THE SECTION 



AVICULARIA. 



B. L. Roknison. 



(Plate 35.) 



It has long been known to several careful observers that our 

 Polygonums of the Section Avicularia (Bird's Knotgrasses) still offer 

 many perplexing problems. Even some of the commoner forms of 

 this group fail to find recognition or adequate characterization in 

 current manuals, and the section is rendered difficult alike by a gen- 

 eral habital similarity, inconspicuous flowers without very striking 

 differences, and by the puzzling seasonal changes through which the 

 individual often passes from spring to autumn. Thus, at the outset 

 nearly all forms of this section tend to be suberect, and, if the condi- 

 tions of growth are at all favorable, produce upon the main stem 

 lanceolate or more often elliptical leaves, which are relatively large 

 (often 2 to 4 cm. long). With the successive branching, which in 

 P. aviculare commonly starts at the very base, the plants in many 

 cases quickly derive a different habit, since the branches are often 

 quite prostrate and always bear leaves of smaller and smaller size. 

 It thus comes about that an old sprawling specimen which has shed 

 all its earlier foliage and retains only the much reduced leaves of the 

 ultimate branchlets possesses so little likeness to the earlier stages of 

 the same plant as to be easily taken for a distinct species. The 

 difference is frequently heightened by changes of color and by the 

 degeneration of the stipules, which are at first whole and white or 

 often silvery, but later turn to brown bristle-formed shreds. To 

 these matters which, however perplexing to the beginner, should not 

 long mislead the careful student, there are added more serious diffi- 



