370 P.UCKWIIEAT FAMILY. 



3. POLYGONUM, KNOTWEED, JOIXTWEED. (Greek: many- 

 jointed.) C'hietly weeds ; some with rather showy flowers; the follow- 

 ing are the coiuinonest ; flowers late suuiiner and autumn. 



§ 1. Floirers ahmri the stem, nearhj sessile in the ojiJs of the almost 

 sessile tiiienr or ohlon(j leaves, smalh r/rcenish-ichitc ; sheaths scarions, 

 nsualli/ clejt or torn and frinijed. 



* Stems leafy throiigliout. 



P. maritimum, Linn. Glaucous, prostrate, the stems stout and short- 

 jointed ; leaves oval to linear-oblong, thick, surpassing the nodes ; stipules 

 very prominent. Seacoast, Mass., S. 2/ ® 



P. aviculare, Linn. Common Kxotwked or Doorwekd. Generally 

 prostrate or creeping, bluish-green, growing everywhere in liard soils 

 about yards, the stems and roots strong ; leaves small, oblong or lanceo- 

 late, acute or acutish ; sepals very small, green and jjinkish. ® 



P. erectum, Linn. Erect or ascending, loose in habit, l^-^"^ ; leaves 

 oblong or oval and obtuse ; flowers larger than in the last, on more evi- 

 dent pedicels. Roadsides. ® 



* * Stems irith much reduced or hract-Uke leaves above. 



P. ramosissimum, Michx. Nearly erect, much branched, and rigid 

 striate stems •J.'^-i° high ; lanceolate or linear leaves tapering into a 

 petiole, and a glossy akene ; sepals 6 and stamens or 3, or else sepals 

 5 with 4 or 5 stamens. Mass., \V. 



P. tenue, Michx. Slender, upright, with thread-like branches, along 

 which the upper flowers form a loose leafy spike ; leaves narrow linear, 

 acute ; akene shining. Dry soil, N. Eng. , S. and W. ® 



§ 2. Flowers collected in terminal S2nlces or spike-like racemes, rose-imrple 

 or flesh-color, or rarely lohite or greenish. 



* Leaves lanceolate, oblong, or ovate, chiefly petioled ; sheaths cylindrical ; 

 flowers several from each bract of the spike, 5-parted. 



-t- Sheaths and bracts not ciliate {except rarely in the first) nor fringed, 

 the sheaths icithout a border; sepals not punctate ; style '2-cleft. 



++ ® Spikes narrow or loose; leaves narrow. 



P. Iapathif61ium, Linn. Tall, \°-CP high ; leaves tapering from near 

 the base to a narrow point (4 '-12' long); glabrous, or the peduncles 

 rough with scattered sessile glands ; spikes linear, nodding ; flowers 

 flesh-color or pale rose ; the 6 stamens and 2 styles included ; akene flat, 

 with concave sides. Wet places, N. Eng., W. Very variable, one form 

 (var. incanum") witli leaves hoary beneatb. 



P. Pennsylvanicum. Linn. Stems l°-3° high, the branches above 

 and peduncles bristly with stalked glands ; spikes oblong, short and blunt, 

 erect; flowers ro.se-purplc ; stamens 8. a little protruding; style 2-clef t ; 

 akene with flat sides. Common in moist places. 



•*-►•*-* 2/ Spikes nsHiilhj heary and dense ; leaves broad. 



P. amphibium, Linn. \Vati:u P. Chiefly N.; in water, stems root- 

 nag below, often sim])le, bearing a single ovate or oblong dense spike or 

 head of pretty large and showy ro.se-red flowers ; leaves rather thick, 

 oblong, heart-oblong, lance-ovate or lanceolate, mostly long-petioled, 

 often Mnnting ; stamens'). 



P. Muhlenb^rgii, Watson. Decumbent or nearly erect, rough with 

 short appre.ssed or glandular hairs ; leaves thinnish, broad-lanceolate and 

 large, long-acuminate; .spike l'-;J' long. Generally in muddy places, 

 N. Eng., W. and S. 



