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. 

 Sepals slightly petaloid, rather narrow, scarcely overlapping and appressed 



1. P. maritimum. 

 achene acuminate. 



2. P. Fowleri. 



5. P.aviculare. 



6. P.neglectum. 



P. atlanticum. 



10. P. ereclum. 



11. P.ramosissimum. 



Plants erect ; achene narrow. 



Flowers hidden in the ocreae; sepals about Yz" long; achene slender. 3. p. leptocarpum. 



Flowers exserted; sepals i"-i^" 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 i^" long at maturity. 

 Achenes with striate faces. 



Mature sepals over W long; achenes acute. 

 Mature sepals less than %" long; achenes acuminate. 

 Achenes with granular or nearly smooth faces. 



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



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



8. P. prolificum. 



Pedicels exserted; sepals over ij4" l n S 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. 



12. P. triangulum. 

 ** Stern 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. PI. 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"-is" 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"-2j" 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. 



