564 POLYGONACEAE. 
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27. Polygonum ramosissimum Michx. 
Bushy Knotweed. (Fig. 1344.) 
P. ramosissimum Michx. F1. Bor. Am. 1; 237. 1803. 
Annual, bright green or yellowish green, gla- 
brous, stem erect or ascending, usually very much 
branched, slender, striate, usually rigid, 4’-4° tall. 
Leaves lanceolate or linear-oblong, short-petioled, 
3/’-20’’ long, acuminate at both ends, persistent, 
conspicuously jointed to the ocreae; ocreae oblique, 
funnelform, few-nerved, becoming deeply lacerate; 
flowers several together in the axillary clusters, 
short-pedicelled; calyx 5-6-parted, greenish-white; 
stamens 6 or fewer; style very short, 3-parted to the 
base; achene 3-angled, acute, sometimes slightly 
protruding beyond the calyx, nearly 114’ long, 
black, reticulated, dull. 
In saline soil, Minnesota to the Northwest Territory, 
New Mexico and California, and on the Atlantic coast 
from Maine to New Jersey. July—Sept. 
Polygonum ramosissimum prolificum Small, Bull. Torr. Club, 21: 171. 1894. 
Bushy, much branched, stem nearly erect, its internodes short, its nodes giving off 2 or more 
branches; leaves narrower; flowers and achenes more numerous. Nebraska and Kansas; also on 
the coast of Maine. 
28. Polygonum camporum Meisn. 
Prairie Knotweed. (Fig. 1345.) 
P. camporum Meisn. in Mart. Fl. Bras. 5: 21. 1855. 
Annual or perennial, glabrous, stem mostly 
erect, slightly striate, much branched, some- 
times slightly glaucous, 2°-3° tall. Leaves 
linear-lanceolate or oblong, soon falling away, 
subsessile, rather obtuse at the apex, veined be- 
neath, 3/’-12’’ long; ocreae funnelform, early 
lacerate and fugacious, dark brown; flowers sev- 
eral together in the axillary clusters, slender-ped- 
icelled; pedicels short; stamens 8; style short, 
3-parted; achene pyramidal-ovoid, 3-angled, 
black, nearly 114’’ long, smooth, shining. 
"On prairies, Nebraska to Louisiana and New 
Mexico. Alsoin South America. July-Sept. 
29. Polygonum ténue Michx. Slender 
Knotweed. (Fig. 1346.) 
Polygonum tenue Michx. Fl. Bor. Am. 1: 238. 1803. 
Annual, glabrous, somewhat rough about the 
nodes, stem very slender or filiform, erect, simple 
or branched, somewhat 4-augled, 4/-12’ tall. 
Leaves linear or linear-lanceolate, sessile, acumi- 
nate at the apex, 2’’-12’’ long, articulated to the 
ocreae, I-ribbed with a lateral impression on each 
side of the rib, the margins minutely scabrous or 
serrulate; ocreae funnelform, soon lacerate; flowers 
several in the axillary clusters, green, subsessile; 
calyx-lobes whitish; stamens 8; style 3-parted nearly 
to the base, its branches diverging; fruit erect; 
achene 3-angled, black, 1’//-1%’’ long, reticulated 
on the angles, the centre of its faces smooth. 
Dry soil, Ontario to Minnesota, Georgia and Arkan- 
sas. Ascends to 3coo ft. in North Carolina. July-Sept. 
