360 POLYGONACEAE (BUCKWHEAT FAMILY) 



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

 Alaska and Greenl. (Eurasia.) 



3. PERSICAllIA [Tourn.] L. Flowers in dense spikes, with small scarious 

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

 naked or ciliate-f ringed or margined ; calyx colored, 5-parted, appressed to 

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



Sheaths nearly or quite free from dilation. 

 Annual; achene compressed. 



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

 Faces of the achene concave ; style and stamens included. 

 Achene 2.5-2.9 mm. broad. 



Leaves glabrous beneath 16. P. pennsylvanicum. 



Leaves more or less flocculent-tomentose beneath, or tardily 



glabrate 12. P. tomentoftum. 



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



Perennial. 



Spikes several in pedunculate panicles 13. P. densiftorum. 



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. amphibium. 



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



peduncles hispid, often glandular 15. P. Muhlenbergii. 



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. orientale. 

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

 Perennial. 



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



Sheaths without herbaceous border. 



Appressed-bristly 23. P. setaceum. 



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 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. 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. 

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

 with red dots. 



12. P. toment6sum 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 ground, Nfd., e. Canada, 

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

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

 lapathifolium, 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 lurbinate, much exceeded by 

 the 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. Perennial, aquatic or rooting in the mud, glabrous or 

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

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



