46 



A new Polygonum from Bolivia. 



By John K. Small. « 



(Plate 293.) 



Polygonum fallax n. sp. 



Annual or perennial by a long somewhat spiral root, low, dull 

 green. Stem more or less densely and caespitosely branched near 

 the top of the root, the branches spreading or prostrate and as- 

 cending, 2-12 cm. long, very leafy except at the base; leaves 

 varying from ovate-oblong to obovate-oblong, 3-5 mm. long, ob- 

 tuse, somewhat revolute and crisped, narrowed at the base, wrinkled 

 above, slightly nerved beneath, the mid-nerve keeled beneath, es- 

 pecially near the base, obliquely articulated at the base of the 

 ocreae ; ocreae funnelform, 4 mm. long, imbricated, especially to- 

 ward the ends of the branches, at length lacerate to a little below 

 the middle; flowers numerous and often crowded; calyx 2.5 mm. 

 long, 5 -parted, 4 segments green, with whitish margins, i wholly 

 included and hyaline, all rounded at the apex, stamens usually 

 5 or 6; filaments dilated their whole length into a broadly ovate 

 hyaline petal-like organ; style two-parted, .4 mm. long; achene 

 lenticular, ovoid, 2.5 mm. long, reddish, nearly smooth, shining, its 

 faces convex, its angles rounded, sometimes faintly margined. 



A species of especial interest collected in Bolivia by Mr. Bang 

 and communicated to me by Dr. Rusby. Although it belongs to 

 the subgenus Aviculariay its fruit possesses characters heretofore 

 unknown in that subgenus. The several natural groups of Polyg- 

 onum bear two kinds of achenes, some lenticular, others trique- 

 trous, while in a few cases both forms appear. Aviculmia has 

 been known to produce only the triquetrous achenes developed 

 from a three-angled ovary with a more or less three-branched 

 style, but in Polygonuui fallax we are confronted with a species of 

 subgenus Avicularia bearing only lenticular achenes developed 

 from lenticular ovaries with two-branched styles. 



A second peculiarity is exhibited in the pericarp which most 

 closely resembles that of the different members of the subgenus 

 Diiravia, both in texture and color, but the styles are not those of 

 that group. Another interesting point is found in the androecium ; 

 the filaments are dilated into broad petal-like organs, which form 

 a cup around the ovary. I know no other case like this in the 



