376 



POLYGONACEAE 



lated at the base of the calyx : calyx greenish or reddish, 4-5 mm. long, somewhat curved : 

 sepals unequal : stamens 4-5 : styles long-exserted, recurved and curled at the tips : achenes 

 lenticular, 3.5-4 mm. long, ovoid-oblong, dark brown or cream-colored, smooth and shin- 

 ing. \_Polygonum Virginianum L. ] 



In woods and thickets, Nova Scotia to Minnesota, Nebraska, Texas and Florida. Summer and fall. 



8. PERSIC ARIA Adans. 



Annual or perennial often pubescent or glandular caulescent herbs, various in habit, 

 never twining nor climbing. Leaves alternate : blades entire, continuous with the ocreae, 

 often glandular-punctate. Ocreae cylindric, mostly membranous, truncate, naked, ciliate 

 or fringed with bristles. Racemes spike-like, varying from linear to ovoid, dense and 

 erect, or few-flowered, lax and drooping. Ocreolae funnelform. naked, ciliate or fringed. 

 Pedicels rather stout, articulated at the base of the calyx. Calyx more or less colored, 

 varying from white and green to red, often glandular-punctate, investing the achene. 

 Sepals mostly 5, 2 wholly exterior, 2 wholly interior and 1 with one margin interior and 

 the other exterior, none of them winged or keeled. Stamens varying from 4 to 8, included 

 or exserted : filaments not dilated, erect or nearly so. Styles mostly 2, sometimes 3, usu- 

 ally partially united, included or exserted : stigmas capitate. Achene mostly lenticular 

 sometimes 3-angled and lenticular on the same plant, usually black, smooth or granular 

 Endosperm horny. Cotyledons accumbent. The plants bloom in the summer and fall, or 

 earlier in the southern part of the range. SMART WEED. 



Raceme usually solitary and terminal : plants aquatic. 1. P. emersa. 



Racemes several or numerous : plants mostly terrestrial. 



Ocreae naked or fringed, not spreading at the top : cotyledons accumbent. 

 Ocreae truncate and naked at maturity. 

 Racemes erect. 



Achenes strongly biconvex. 2. P. Portoricensis. 



Achenes flat. 



Style-branches conspicuously exserted. 3. P. longistyla. 



Style-branches included. 



Achene gibbouspn one side, ovoid : leaf-blades linear or linear- 



lanceolate. 4. P. Mcxicana. 



Achene flat, orbicular or broader than high : leaf-blades lan- 



ceolate or broadly-lanceolate. 5. P. Pennsylvanica. 



Racemes drooping, or with drooping tips. 



Styles united only at the base. 6. P. incarnata. 



Styles united to above the middle. 7. P. lapathifolia. 



Ocreae fringed with bristles (except a variety of no. 15). 

 Racemes erect. 



Flower-clusters contiguous or mainly so. 

 Achenes lenticular. 



Ocreae with short inconspicuous bristles. 



Racemes linear. 8. P. segeta. 



Racemes oblong. 9. P. persicarioides. 



Ocreae with long conspicuous bristles. 10. P. Persicaria. 



Achenes 3-angled. 



Stems or ocreae glabrous or strigose : leaf-blades neither 



rounded nor cordate at the base. 

 Racemes oblong. 



Ocreae inconspicuously fringed : achenes narrowly ovoid. 9. P. persicarioides. 

 Ocreae conspicuously fringed : achenes broadly ovoid. 10. P. Persicaria. 

 Racemes linear. 



Ocreolae conspicuously fringed. 11. P. Opctousana. 



Ocreolae inconspicuously fringed. 



Leaf-blades mainly glabrous above : achenes pointed 



at the apex. 12. P. hydropiperoides. 



Leaf-blades strigose above : achenes pointed at both 



ends. 13. P. setacea. 



Stems or ocreae copiously hirsute : leaf-blades rounded or cor- 



date at the base. . 14. P. hirsuta. 



Flower-clusters mostly separated. 15. P. punctata. 



Racemes drooping. 



Leaf-blades lanceolate or linear-lanceolate: achenes smooth and 



shining. 16. P. minor. 



Leaf-blades ovate or ovate-lanceolate : achenes granular and dull. 17. P. Hydropipcr. 

 Ocreae with spreading, fringed tops : cotyledons incumbent. 18. P. orientalis. 



1. Persicaria emersa (Michx. ) Small. Perennial, often strigose throughout. Stem 

 more or less creeping in wet places, the distal end erect, 3-8 dm. long, mostly simple, 

 leafy, enlarged at the nodes, lower parts becoming hollow : leaf-blades broadly-lanceolate 

 or oblong-lanceolate, sometimes narrowly-lanceolate, 5-20 cm. long, acute or acuminate at 

 the apex, rounded, cordate or truncate at the base, the lateral nerves prominent, often fork- 

 ing : ocreae 2-3 cm. long, the younger clasping the stem, eciliate : raceme narrow, 3-10 



