66o 



POLYGONACEAE. 



Vol. I. 



* Stem, and branches terete and usually striate. 

 tAchenes much exserted from the calyx. 

 Plants prostrate ; achene broad. 



Sepals decidedly petaloid, very broad, much overlapping and lax at maturity ; achene acutish or 



blunt. i. P.maritimum. 



Sepals slightly petaloid, rather narrow, scarcely overlapping and appressed ; achene acuminate. 



2. P. Fowleri. 

 Plants erect ; achene narrow. 



Flowers hidden in the ocreae ; sepals about Vz" long ; achene slender. 

 Flowers exserted; sepals i"-iJ4" long; achene stout. 



tf Achenes included in the calyx, or exposed at the tip. 



Sepals with white or pink margins. 



Pedicels not exserted from the ocreae; sepals less than i%" long at maturity. 

 Achenes with striate faces. 



Mature sepals over W long; achenes acute. 5. 



Mature sepals less than %" long ; achenes acuminate. 6. 



Achenes with granular or nearly smooth faces. 



Plants prostrate; leaves broad; mature sepals about 54" long. 

 Plants erect or nearly so ; leaves narrow ; mature sepals about 1' 



3- 



leptocarpum. 

 exsertum. 



aviculare. 



long. 



7. P. buxiforme. 



Pedicels exserted; sepals over i}4" long at maturity. 

 Sepals with yellowish or greenish margins. 

 Leaves broad ; achene mostly dull. 

 Leaves narrow ; achene mostly shining. 



Achenes much longer than wide ; mature calyx tapering at the base. 



Achenes about as wide as long ; mature calyx auriculate-cordate at the base. 



8. P. prolificum. 



9. P. atlanticum. 



10. P. ereclum. 



11. P.ramosissimum. 



** Stem and branches angled. 



Leaves plicate ; fruiting pedicels short, erect. 



Leaves flat, margins revolute ; fruiting pedicels long, deflexed. 



12. P. triangulum. 



P. tenue. 

 P. Douglasii. 



i. Polygonum maritimum L. Seaside Knot- 

 weed. Fig. 1615. 



Polygonum maritimum L. Sp. PI. 361. 1753. 

 Polygonum glaucum Nutt. Gen. 1 : 254. 1818. 



Perennial, glaucous, often nearly white, glabrous, 

 root usually deep, woody, stem prostrate or ascend- 

 ing, branched, 8'-2o' long, deeply striate. Leaves 

 oblong, elliptic or sometimes ovate, mostly equalling 

 or longer than the internodes, 3"-i2" long, fleshy, 

 veined beneath, somewhat rugose above, the margins 

 often revolute; ocreae large, silvery, at length lacer- 

 ate, becoming brown at the base; flowers 1-3 to- 

 gether in the axils, becoming slender-pedicelled ; 

 sepals white or pinkish, the margins decidedly pink; 

 achene 3-angled, ovoid, ii"-2" long, acute or blunt, 

 smooth, shining, longer than the calyx. 



In sands of the seashore, Massachusetts to Florida. 

 Also on the coast of Europe. Coast knot-grass. July- 

 Sept. 



2. Polygonum Fowleri Robinson. 

 Fowler's Knotweed. Fig. 1616. 



Polygonum Fowleri Robinson, Rhodora 4: 67. 1902. 



Perennial, glabrous, pale green or slightly glau- 

 cous, stem 3'-24' long, prostrate, usually much 

 branched, striate. Leaves ovate-lanceolate, ob- 

 long or obovate, 3"-i5" long, short-petioled, ob- 

 tuse or abruptly pointed at the apex, veined 

 beneath, inconspicuoulsy so above, shorter than 

 the internodes or equalling them; ocreae becom- 

 ing lacerate, silvery, brown and glaucous at the 

 base when old ; flowers 2-4 together in the axils ; 

 sepals greenish, or the margins white or pinkish; 

 achene ovoid, 3-angled, 2"-2$" long, slightly 

 granular but shining, acuminate, exceeding the 

 calyx. 



■In waste places, New Brunswick, Anticosti and 

 Quebec to Maine. Also from Alaska to Washington. 

 May-Sept. P. Rayi Babington, with which this was 

 confused in our first edition, is not definitely known 

 to occur on this continent. 



