282 



WEEDS AND USEFUL PLANTS. 



§ 2. Stem weal, not twining hut somewhat climbing or supported on other 



plants by means of the prickles on the angles of the stem and petioles, 

 6. P. arifo'liuni, L. Leaves halberd-shaped, acuminate, on long 

 petioles ; clusters racemose, few-flowered ; peduncles glandular-hispid ; 

 stamens 6 ; styles 2 ; fruit lenticular. 



Arum-leaved PolygonuzvI. Halberd-leaved Tear-thumb. 



Root annual. Stem 3-6 feet long, rather coarse, grooved-angled, branching, often pur- 

 ple. Leaves 2-5 inches long, and 1-3 inches wide,— the midrib and nerves hirsute ; pe- 

 holes half an mch to 3 inches long, retrorsely aculeate. Stipules ciliate. Calyx often of 4 

 connected sepals, purple, with the margins pale red. 



^Swampy low grounds, along rivulets, &c. : throughout the United States. Fl. Aug. 



Obs. This and the following species 

 often grow in company, — clamber- 

 ing over other plants, and forming 

 entangled bunches. Both are worth- 

 less, unwelcome weeds, especially 

 among the second crop of wet mead- 

 ows. Ditching and draining are the 

 remedies for the evil. 



7. P. sagitta'tnm, L. Leaves 

 arrovv-shaped, acute, cn short pe- 

 tioles ; clusters capitate ; peduncles 

 smooth ; siameus 8 ; styles 3 ; fruit 

 sharply 3-angl^d. 



Sagittate Polygonum. 

 leaved Tear-thumb. 



Arrow- 



Eoct annual. Stem 2-4 feet long, slender, 

 branching, acutely quadrangular. Leavesl-3 

 inches long, and half an inch to an inch wide, 

 sagittate at base, — the midrib and petiole re- 

 trorsely aculeate. Sti2?ules smooth. Sejjals 

 pale red, with the margins nearly white. 



Swampy meadows and thickets : Xew 

 York to Florida. Fl. August. Fr. Septem- 

 ber. 



Obs. Several other species of 

 Polygonum are met with about our 

 farms (descriptions of which may He 

 found in the Floras), — but, as they 

 are not particularly troublesome, 

 they are omitted here. 



Fig. 182. The Arrow leaved Tear-thumb (rolygonum sagittatum). 



