46 
A new Polygonum from Bolivia. 
By JouHn K. SMALL. 
(PLATE 293.) 
POLYGONUM FALLAX f. 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, 1 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, 1S _ 
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 Avicu/aria, 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. Avicularia 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 Polygonum 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 — 
Duravia, 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 — 
