aT J 
ie . 
- 
+ 
Polygonaceae 7 
C. Fruit reflexed. 
D. Sheaths 3—5 mm. long; leaves averaging less than 13 mm. long: E. . (P. 
austinae. ) P. engelmannii Gr. 
DD. Sheaths 10—25 mm. long; leaves averaging 25 mm. long or longer. 
E. Upper bracts lanceolate to oblong, foliaceous. E. (P. douglasii mon- 
tanum. ) P. montanum Gr. (Mountain Knot-weed) 
EE. Upper bracts subulate, small. 
F. Flowers funnelform, 2-3 mm. long; sheaths |1—13 mm. long. W. 
\ (Gaal Ss P. douglasii Gr. (Douglas Knot-weed) 
FF. Flowers campanulate, 3.54.5 mm. long; sheaths about 20 mm. 
long. E., P. majus Pip. 
CC. Fruit erect or spreading. 
G. Plants prostrate-spreading. 
Akene not exceeding the calyx. 
I. Leaves not conspicuously veined, not notably thick; akenes dull. W. E. 
P. aviculare L. (Door-weed) 
II. Leaves conspicuously veined, thick; akenes slightly shining. W. (P. 
littorale.) P. aviculare littorale Koch (Shore Knot-weed) 
HH. Akene projecting beyond the calyx. W. 
F. fowleri Rob. 
GG. Plants erect or ascending. 
J. Leaf margin serrulate-scabrous; akene smooth, shining. U. 
FP. howellii Gr. 
JJ. Leaf margin entire. 
K. Leaves rather wide, scarcely reduced toward the stem-tip. 
L.. Plant 20—60 cm. high, not alpine; leaves 1.2—-12.5 cm. long; 
akenes mostly granular, dull. W. E. 
EF. erectum L. (Hrect Knot-weed) 
LL. Plant 2.5—7.5 cm. high, alpine; leaves 0.51.2 cm. long; 
akenes smooth, shining. C. E. 
P. minimum Wats. (Alpine Knot-weed) 
KK. Leaves narrow, decidedly reduced toward stem-tip; akenes smooth, 
shining. 
M._ Plant branched thruout; leaves acuminate; flowers in the axils of 
the upper leaves; stamens 3—6. E. 
P, ramosissimum Michx. (Bushy Knot-weed) 
MM. Plant, branched only from base; leaves acute: flowers in the 
axils of almost all the leaves; stamens 6—8, E. 
P. sawatchense Small 
BB. Flowers ‘in terminal bracted spike-like racemes. 
N. Leaves more or less revolute; spike-like racemes hardly interrupted, rather 
dense; perianth with some pink or red. 
O. Plants minutely puberulent thruout; stem prostrate or ascending. W. 
P, lineare Hook. 
OO. Plants glabrous thruout; stem erect. 
P. Sheaths 2—4 mm. long; filaments dilated at base. W. C. E. 
PF, nuttallij Small (Pink Knot-weed) 
‘ PP. Sheaths 8—15 mm. long; filaments not dilated at base. W. 
P. spergulariaeforme Meisn. 
NN. Leaves not revolute; spike-like racemes interrupted but rather closely so; 
perianth pinkish or white or green. 

