280 WEEDS AND USEFUL PLANTS: 
PR age AS Sa PRS I hy a ee 
4. P. Hydropi’per, L. grmere very acrid ; leaves lanceolate, pellucid- 
dotted, wavy margined ; sh eaths ciliate with shortish bristles; racemes 
eee and nodding ; fascicles few-flowered, rather distant ; ealyx 
Fig. 179. The Pennsylvanian Polygonum (P. Pennsylvanicum. ck in aaa 
flower, opened. " x i ; ) Sf oat 
