138 Polvgonaceae 
Q. Bracts of the inflorescence white-margined; stamens 8. W. E. 
P. polygaloides Meisn. ; 
QQ. Bracts of the inflorescence not white-margined; stamens fewer. 
R. Plant branched from base; styles none or almost none; akene brown, 
smooth. C. E. P. kelloggii Gr- 
RR. Plant simple; style evident; akene black, striate. E. (P. conferti- 
florum. ) P, watsoni Small ; 
AA. Plants perennial, glabrous; stems shrubby, chestnut-brown; bark loose-scaly. 
S. Seacoast plant, in sandy soil; leaves strongly revolute; sheaths 12—21 mm. long; 
flowers in subspicate clusters near the ends of the branches. W. 
Pp. paronychia (Oe Sa 185 (Shrub. Knot-weed) 
SS. Mountain plant, in rocky soil; leaves not revolute; 4—6 mm. long; flowers 
2—23 together in the exils of the leaves. C. E. 
P. shastensis Brew. (Shasta Knot-weed) 
Subgenus DURAVIA (3-VEINED KNOTWEED)—Herbs, annual, low, erect, very 
slender, branching. Flowers solitary, sessile, in the axils of foliaceous bracts. Leaves 
_ yery narrow, rigid, not jointed on the petiole, strictly 3-veined; stipules fimbricate or 
2-lobed. Perianth colored, 5-parted, appressed to the akenes. Stamens 8; inner fila- 
ments scarcely dilated. Styles 3, persistent. Akene 3-angled. 
A. Akene obovate; spike rather stout. 
B. Sheath.6—8 mm. long, its segments rigid; upper leaves reduced. E. 
P. greenei Wats. 
BB. Sheath 2—3 mm. long, its segments not rigid; leaves much the same size 
thruout. E. P. parryi Gr. 
AA.  Akene narrowly lanceolate; spike very slender; sheath about 2 mm. long; upper 
leaves reduced. W. C. P. californicum Meisn. 
Subgenus* PERSICARIA (SMART-WEED)—Flowers fascicled in spikes, with 
small scarious bracts; spikes usually dense. Leaves not jointed on the petiole, pinnately 
many-veined; sheaths cylindric, truncate, scarious, entire, naked or ciliate-fringed. _ Peri- 
anth colored, 5-parted, appressed to the akene. Stamens 4—8; filaments filiform. Stig- 
mas 2—3. Akene 3-angled or lens-shaped. 
A. Sheaths bristly-ciliate. : 
B. Sepals dotted with dark glands; annual; akene lens-shaped or 3-angled. 
C. Racemes drooping; akene granular or dull. W. E. 
P. hydropiper Lb. (Water Pepper) 
CC. Racemes erect; akene smooth, shining. 
D. Spikes distinctly peduncled. W. E. 
‘ P. punctatum Ell. (Dotted Smart-weed) 
DD. Spikes not distinctly peduncled.  E. 
P. punctatum leptostachyum Small 
BB. Sepals not dark-dotted. 
E. Spike 3—6 cm. long, slender, not dense, interrupted; style 3-cleft; akene 
3-angled. W. E, P. hydropiperoides Michx. (Mild Water Pepper) 
EE. Spike 1.2—-3.5 cm. long, thick, dense, not interrupted except sometimes at 
base; styles 2 or 2-cleft, rarely 3-cleft; akene lens-shaped, rarely 3-angled. 
F. Leaves mostly with a dark blotch near the middle; plant glabrous, never 
aquatic; spikes several. W. E. 
P. persicaria L. (Lady’s Thumb) 


