66o 



POLYGOXACEAE. 



VOL. 1. 



* 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. Fowler i. 

 Plants erect ; achene narrow. 



Flowers hidden in the ocreae ; sepals about ^2" long ; achene slender. 3. P. leptocarpum. 



Flowers exserted; sepals i"-ij<$" long; achene stout. 4. P. exsertum. 



ttAchenes included in the calyx, or exposed at the tip. 



Sepals with white or pink margins. 



Pedicels not exserted from the ocreae; sepals less than iJ4" long at maturity. 

 Achenes with striate faces. 



Mature sepals over 34" long; achenes acute. 5. P.aviculare. 



Mature sepals less than 34" long; achenes acuminate. 6. P.neglectum. 



Achenes with granular or nearly smooth faces. 



Plants prostrate ; leaves broad ; mature sepals about 34" long. 7. P. buxiforme. 



Plants erect or nearly so; leaves narrow; mature sepals about i" long. 



8. P..prolificum. 



Pedicels exserted; sepals over i*4" long at maturity. 9. P. atlanticum. 



Sepals with yellowish or greenish margins. 



Leaves broad; achene mostly dull. 10. P. ereclum. 



Leaves narrow ; achene mostly shining. 



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

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



12. P. triangiilum. 

 ** Stem and branches angled. 



Leaves plicate; fruiting pedicels short, erect. 13- P.'tenue. 



Leaves flat, margins revolute; fruiting pedicels long, deflexed. 14. P.Douglasii. 



i. Polygonum maritimum L. Seaside Knot- 

 weed. Fig. 1615. 



Polygonum maritimum L. Sp. PL 361. 1753. 

 Polygonum glaucum Nutt. Gen. i : 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"-2i" 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. 



