a60 POLYGONACEAE (BUCKWHEAT FAMILY} 



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

 Alaska and Greenl. (Eurasia.) 



§.3. PERSICArIA [Toum.] L. Mowers in dense spikes, with small scarious 

 bracts; leaves not jointed on the petiole; sheaths cylindrical, truncate, entire, 

 naked or ciliate-fringed or margined ; calyx colored, 6-parted, appressed to 

 the fruit ;. stamens i-S ; 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. longiat^hl/ni. 



Faces of the achene concave ; style and stamens included. 

 Achene 2..')-2.9 ram. broad. 



Leaves glabrous beneath 16. P. peimaylvamieum. 



Leaves more or less flocculent-toinentose beneath, or tardily 



glabrate 12. P. toinentoffwm.. 



Achene 1.5-2 mm. broad 11. P. lapathifolivm. 



Perennial. 



Spikes several in pedunculate panicles 18. i*. denazjlorum. 



Spikes solitary 'Or in pairs. 

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

 duncles glabrous or nearly so 14, P. ampMbi'wm. 



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



peduncles hispid, often glandular , 16. P. MuhleribergU. 



Sheaths bristly-ciliate. 



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



Stem and peduncles not glandular-hispid. 

 Sepals dotted with dark glands. 



Achene dull 19. P. Hydropiper. 



Achene shining 20. P. acre. 



Sepals not dark-dotted. 

 Annual. 

 Leaves ovate ; sheaths often with an herbaceous border . 21. P. orieniale. 



Leaves lanceolate ; sheaths without herbaceous border . . 22. P. PerHcaria. 

 Perennial. 

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



Sheaths without herbaceous border, 



Appressed-bristly 28. P. aetaceum. 



Finely, strigose or smoothish 24. P. hydropiperoides. 



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 cUiolate ; 

 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. broad. 

 (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. 

 nod6sum ( Vers. ) Weinmann is a stout form with strongly nodose stems spotted 

 with red dots. 



12. P. tomentbsum 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 tomentum on the under surface; 

 peduncles distinctly glandular; spikes thickish, the lateral scarcely peduncled; 

 flowers larger and mostly paler than in the last. — Moist gi'ound, Nfd., e. Canada, 

 and N, E, to Cal. and B. C. (Eu.) Passes to the usually dwarf var. inoXnuji 

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

 lapalhifolinm, var. Koch.) — Sandy shores, sphagnum bogs and occasionally. on 

 rubbish heaps, N. E. to N, J. and westw., chiefly along the Great Lakes. (Eu.) 



13. P. densiflbrum Meisn. Perennial, very stout ; leaves lanceolate, atten- 

 uate at each end, 2-3 dm. long, 3-6 cm. broad ; spikes several, slender, densely 

 flowered, rather rigidly erect, paniculate ; sheaths turbinate, much exceeded by 

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

 and shining, 1.6 mm. broad. (^P. portoricense Bertero.) — S. Mo. to S. C, La,, 

 and Tex. (Trop. Am.) 



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

 nearly so, rarely branching above the rooting base ; leaves usually floating, 

 pmooth and shining above, mostly long-petioled, elliptical to oblong or some- 



