3<>0 I'OLYGONACEAE (BUCKWHEAT FAMILY) 



lanceolate. Alpine summits of N. E., shores of L. Superior, Col., and Utah to 

 Alaska and Greenl. (Eurasia.) 



3. PERSICAlUA [Tourn.] L. Flowers in dense spikes, icith small scario us 

 bracts; leaves not jointed on the petiole ; sheaths cylindrical, t.rtnu-nte. entire, 

 naked or ciliate-fringbd or margined ; calyx colored, ^-parted, appressed to 

 the fruit ; stamens 4-8 ; filaments filiform ; cotyledons accumbent. 



Sheaths nearly or quite free from ciliation. 

 Annual; achene compressed. 



Faces of the achene umbonate ; style or stamens exserted . . 17. P. lonyixtyfuin. 

 Faces of the achene concave ; style and stamens included. 

 Achene 2.5-2.9 mm. broad. 



Leaves glabrous beneath 16. P. pennnylnanicum. 



Leaves more or less flocculent-tomentose beneath, or tardily 



glabrate 12. P. tomentoimm. 



Achene 1.5-2 mm. broad 11. P. l<t]><itli (folium. 



Perennial. 



Spikes several in pedunculate panicles 13. P. denHiflorum. 



Spikes solitary or in pairs. 



Leaves elliptical, obtuse or acuto ; spikes 1.2-2.4 cm. long; pe- 

 duncles glabrous or nearly so 14. P. amphibia in. 



Leaves lanceolate or ovate, acuminate; spikes 3-10 era. long; 



peduncles hispid, often glandular 15. P. Muhlenbergii. 



Sheaths bristly-ciliate. 



Stein and peduncles glandular-hispid 18. P. Careyi. 



Stem and peduncles not glandular-hispid. 

 Sepals dotted with dark glands. 



Achene dull 19. P. Hydropiptr, 



Achene shining 20. P. acre. 



Sepals not dark-dotted. 

 Annual. 



Leaves ovate ; ^heaths often with an herbaceous border . 21. P.orienMf. 



Leaves lanceolate ; sheaths without herbaceous border . . 22. P. Pf.rsicar/a. 

 Perennial. 



Sheaths with a spreading herbaceous border (14) P. amphibium, v. 



Sheaths without herbaceous border. 



Appressed-bristly 23. P. 



Finely strigose or smoothish 24. P.hydropiperoide*, 



11. P. lapathifblium L. Annual, branching, 0.6-2.4 m. high, glabrous or 

 the peduncles obsoletely glandular ; leaves lanceolate, attenuate upward from 

 near the cuneate base and acuminate, somewhat scabrous with short appressed 

 hairs on the midrib and margin ; sheaths and bracts rarely somewhat ciliolate ; 

 spikes slender (1-5 cm. long), somewhat panicled, dense, erect or nodding; 

 flowers white or pale rose-color ; stamens 6 ; achene ovate, rarely 2 mm. br<i>/. 

 (P. incarnatum of auth. and ? Ell., the latter merely a robust large-leaved form 

 with long drooping spikes.) Wet places, common and variable. (Eu.) Var, 

 NOIIOSUM (Pers. ) Weinmann is a stout form with strongly nodose stems spotted 

 with red dots. 



12. P. toment&sum Schrank. Annual, simple or moderately branched, 1-5 

 dm. high ; leaves lanceolate or lance-oblong, acute or barely acuminate, at least 

 the lower retaining more or less flocculent lament nm <i the innier .in\f<n; . 

 peduncles distinctly ylandiihn- ; xju'kes thick ish, the lateral scared;/ / <iii<'lrii ; 

 flowers larger itml numtli/ paler than in the last. Moist ground, Nfd., e. ( 'anala. 

 ami N. E. to Cal. and 15. C. (Eu.) Passes to the usually dwarf var. INOAM M 



Schmidt ) (Jiirke with leaves all permanently white-woolly underneath. (P. 

 /n/Hif/ii/nl/inu, var. Koch.) Sandy shores, sphagnum lions and occasionally on 

 rnl.l.ish lieajis. N. E. to N. .1. and westw., chiefly along tin- (ireat Lakes. (Eu.) 

 1'J. P. densiflbrum Meisn. Perennial, very stout ; leaves lanceolate, atten- 

 uate at each end, _?-:! dm. long, :!-(l cm. broad ; xy^'/vx sevenil, slender, densely 

 flowered, rotfuT rit/idh/ r/vr/. /itniint/ifti- ; slti-iitlix tiirnhinti'. much exceeded by 

 the slender pedicels; styles 2; achene dark brown, strongly biconvex, smooth 

 and shining, !."> nun. broad. (P. portoricense Bertero.) S. Mo. to S. C., La., 

 and Tex. (Trop. Am.) 



14. P. amphibium L. Perennial, aquatic or rooting in the mud, glabrous or 

 nearly so, rarely branching above the rooting base; //>vx usually floating, 

 smooth and shining above, mostly louy-petioled, <'lliptical to oblong or some- 



