236 POLYGONACEAE 



styles mostly 2, sometimes 3, usually partially united; stigmas capitate, Achenes 

 mostly lenticular, sometimes 3-angular, usually black, smooth or granular. 

 Endosperm hor^iy; cotyledons accumbent. 



:^emes terminal only and usually solitary; 

 Ocreae without spreading foliaceous tops 

 Plant usually floating, or decumbent ar 

 acute or obtuse. 



1. P. coccinea, 

 pubescent, acumin- 



2. P. Muhlenbergii. 



ate. 



Ocreae with spreading foliaceous tops; leaf-blades narrowly c ..^ ^. .....^^...^.^ 



(Dreader m floating forms), pubescent. 3. P. Hartwrightii. 



Kacemes axillary as well as terminal, numerous; annuals. 

 Ocreae without marginal bristles. 



Racemes erect; glands on the branches and inflorescence numerous, stalked. 



T, „ , . , , , , = 4. P. omissa, 

 Kacemes drooping; glands on the branches and inflorescence sessile. 



Styles united only at the base. 5. p. incarnata. 

 Styles united to about the middle. 



Leaves deep green on both sides, 6. P. lapathifolia. 



Leaves pale beneath. - 7 P inrana 

 Ocreae bristle-fringed. incana, 



Racemes oblong or cylindric. about 1 cm. thick in fruit; perianth not punctate 



usuany pmk to red-purple. 8 P. Persicaria 



Racemes slender, loosely flowered, about 5 mm. thick in fruit; perianth white 



or pale green, copiously punctate. 

 Racemes erect; achenes smooth and shining. 9. P punctata 



Racemes noddmg at least in fruit; achenes granular and dull. 



10. P. Hydropiper, 



1. p. coccinea (Muhl.) Greene. Perennial, glabrous, or the young shoots 

 somewhat pubescent; stem 5-50 dm. long; leaves oblong or elliptic, 3-10 cm. 

 long, glossy, obtuse or acute at both ends, or when growing in mud more elongate, 

 elliptic-lanceolate and acute; raceme spike-like, 1-3 cm. long; perianth light rose- 

 colored; achenes lenticular, black. Polygonum amphibium Hook., notL. Persi- 

 caria plattensts, P. subcoriacea, P. psychrophila, P. oregana, and P. laetevirens 

 Greene. In water or rarely in mud: Me.— N. J.— N.M.— Calif.— Alaska. 

 Platn — Mont. Je-Au. 



, . 2. ^- Muhlenbergii (Meisn.) SmaU. Perennial, more or less strigose- 

 hispid throughout; stem erect or creeping at the base, 3-8 dm. high, simple; 

 leaf-blades broadly lanceolate, 5-20 cm. long, acuminate or acute; racemes spike- 

 like, Imear or hnear-oblong, 3-10 em. long; perianth dark rose-colored, rarely 

 ^iV^T, I™™' ^"^' achenes lenticular, black, granular but shining. Polygonum 

 Muhlenbergii (Meisn.) S. Wats. P. emersum (Michx.) Britton. Per^caria 

 ernersa (Michx.) SmaU. P. propinqua and P. Wardii Greene. In swamps and 

 shallow water : Me.— Va.—N.M.— Calif.— B.C.; Mex. Plain— Submont . Je-S. 



*!, ^' ?• H^^^^ightii (A. Gray) Greene. Perennial, more or less hispid 

 throughout; stem ascending or suberect, 3-7 dm. long, or rarely floating in water; 

 leat-blades narrowly lanceolate or oblong-lanceolate or oblong, 6-18 cm. long; 

 raceme spike-Uke, oblong or ovoid, 1-3 cm. long, erect; perianth rose-colored, 

 d-4.o cm. long; achenes lenticular, 2.5 mm. long, black, smooth and shining. 

 Polygonum Hartwrightii A. Gray. Persicaria muriculata and P. villosula Greene. 



Wet places and shaUow water. Me.— Pa.— Calif.— Wash.— Sask. Plain— 

 bubmont. Je-S. 



4. P. omissa Greene. Annual; stem 3-6 dm. high, with copious stipitate 

 glands; ocreae short, cup-shaped; leaf-blades 5-10 cm. long, lanceolate or oblong- 

 lanceolate, glabrous, punctate; racemes short-oblong or eUipsoid, 1-2 cm. long; 

 perianth deep pink, about 4 mm. long; achenes round-ovate, black and shining, 

 nearly Hat on one side. Polygonum omissum Greene. Wet ground and dried- 

 up ponds: Kans.— Colo. Plain. Jl^. 



^/ ?*i?j^*^?*** ^^^-^ Small, Annual, nearly glabrous throughout; stem 

 erect, t>-10 dm. long, more or less thickened at the nodes; leaf-blades lanceolate 

 or linear-lanceolate, o-20 cm. long, acuminate or acute; racemes linear, 3-8 cm. 

 long, drooping; perianth whitish, green, or rose-colored, 2-3 mm. long; achenes 

 lenticular, rarely 3-angled, dark bro^Ti or black, shinmg, smooth. Polygonum 

 mcarnatum ER. Wet places: Vt.—Fla.— Calif.— Ida. Plain-^Submont Jl-O . 



