cm. long and 1.5-2 cm. thick, the small bracts papery and brownish; pedicels 2-7 

 mm. long; perianth 4-5 mm. long, connate for about one fifth its length, the 5 

 oblong equal segments white to pinkish; stamens 8, exserted, the filaments to twice 

 as long as the perianth, the inner ones broadly flared at the extreme base; styles 3, 

 distinct nearly to base, about 3.5 mm. long; achene triquetrous, yellowish-brown, 

 smooth and shining, about 4 mm. long. 



Bogs, wet meadows, seepage about lakes, old lake beds and in moist humus of 

 conifer forests, in N. M. (Socorro, Grant, Santa Fe, San Miguel and Taos cos.) 

 and Ariz. (Apache, Coconino, Greenlee and Graham cos.), June-Oct.; Mont, to 

 B.C., s. to N. M., Ariz, and Calif. 



14. Polygonum pensylvanicum L. Pinkweed, smartweed. Fig. 407. 



Stout erect annual from a taproot, branching above; stems 3-20 dm. tall, mostly 

 glabrous below to stipitate-glandular in the inflorescence, greenish or reddish; leaves 

 4-22 cm. long, 1-5 cm. wide, lanceolate to broadly lanceolate, acuminate, abruptly 

 tapering to short petioles, sparsely punctate above and below, the veins somewhat 

 strigose, the margins strigose-ciliate; stipular sheaths cylindric-funnelform, gla- 

 brous, truncate and without bristles, membranous and soon fracturing, 10-15 mm. 

 long; spikes mostly compact, rarely interrupted, 2-4 cm. long, erect, the pedun- 

 cles densely stipitate-glandular; sheathing bracts funnelform, the tip acute, glabrous 

 to sparsely glandular, the margins with a few minute cilia toward apex, otherwise 

 entire; pedicels exserted, glabrous; perianth rose to white, 3-4 mm. long, 5-parted 

 to below middle; stamens 8 or less, some in the sinuses of perianth, others from 

 between lobes of the glandular disk; disk prominent, 8-lobed; style 2- or 3-cleft 

 to below middle; stigmas capitate; achene lenticular to trigonous, microscopically 

 roughened, dark-brown to black and shiny, 2.5-3.4 mm. long. Persicaria pensyl- 

 vanica (L.) Small. 



In low marshy ground, mud along irrigation ditches, streams and rivers, and 

 about pools, in (mostly) e. Tex., Okla. (Cherokee, Adair, Johnston and Sequoyah 

 COS.), N. M. (Socorro Co.) and Ariz. (Apache, Coconino, Yavapai, Santa Cruz 

 and Pima cos.), May-Nov.; throughout N.A. 



15. Polygonum amphibium L. Floating knotweed, water smartweed. Figs. 



408 and 409. 



Dimorphic, amphibious, aquatic or terrestrial perennial, rooting at swollen 

 nodes; terrestrial plants erect or decumbent, to about 15 dm. tall; aquatic plants 

 with floating tips and spreading or floating leaves, or at length with erect branched 

 aerial stems; stems at length swollen above the nodes, glabrous to puberulent or 

 finely tomentose; leaves lanceolate-attenuate to oblong-elliptic or ovate, 5-25 cm. 

 long, 1-6 cm. wide, obtuse to acuminate at apex, slightly unequal at the cuneate 

 to truncate or cordate base, finely silky-pubescent, the margins somewhat undu- 

 late; petioles 2-4 cm. long, the lower half decurrent and flanked by a stipular 

 sheath extending as a cylinder around the stem for 10-20 mm. above its junction 

 with the petiole; stipular sheath about 12-nerved and truncate across the top, 

 those of floating or submersed stems glabrous and entire, those of emersed stems 

 scabrous and ciliate-margined, with a few hairs of unequal lengths along the 

 nerves or scattered between them; inflorescence of 1 or 2 elongate densely 

 flowered terminal spikes 1-8 cm. long on a stout red densely glandular-pubescent 

 peduncle 1-3 cm. long; flowers fascicled in the axils of hairy stipulate bracts on 

 short glabrous pedicels, 1 flower of each fascicle blooming at a time, the flowers 

 thus blooming in succession over entire spike; perianth 5-merous, petaloid, bright 

 rose-pink, 4-5 mm. long, the ovate lobes free above but united below; stamens 

 5, inserted just below the sinuses of the perianth lobes, included or exserted 

 (always of different length than the style); anthers versatile; glandular disk at- 



820 



