360 POLYGONACEAE (BUCKWHEAT FAMILY) 



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

 Alaska and Greenl. (Eurasia.) 



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

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

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

 the fruit; stamens -^S ; filaments filiform ; cotyledons accumhent. 



Sheaths nearly or quite free from cUiation. 

 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 tlocculent-tomentose beneath, or tardily 



glabrate 12. /*. tomentosum. 



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



Perennial. 



Spikes several in pedunculate panicles 



Spikes solitary or in pairs. 

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

 duncles glabrous or nearly so 



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



peduncles hispid, often glandular 



Sheaths bristly-ciliate. 

 Stem and peduncles glandular-hispid .,,.,.. 

 Stem and peduncles not glandular-hispid. 

 Sepals dotted with dark glands. 



Achene dull 



Achene shining 



Sepals not dark-dotted. 

 Annual. 

 Leaves ovate ; sheaths often with an herbaceous border 

 Leaves lanceolate ; sheaths without herbaceous border . 

 Perennial. 

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



Sheaths without herbaceous border. 



Appressed-bristly 23. P. setaceum. 



Finely strigose or smoothish 24. P. hydropiperoides. 



11. P. lapathifolium 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 scaljrous with short appressed 

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

 spikes slender (1-5 cm. long), someiohat 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. 

 n-od6sum (Pere.) Weinmann is a stout form ^^•ith strongly nodose stems spotted 

 with red dots. 



12. P. tomentbsum Schrank. Annual, simple or moderately Ijranched, 1-5 

 dm. high ; leaves huiceolate 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. ) Pa.sses to the usually dwarf var. incXmm 

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

 lapathifolium, var. Koch.) — Sandy shores, sphairtuim bogs and occasionally on 

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



13. P. densiflorum 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 

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

 and shining, 1.5 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 murl. glabrous or 

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

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



