POLYGCNACE^. 



301 



anth. Seed with farinaceous albumen and an inverted em- 

 bryo.— Herbaceous plants, rarely shrubs, Avith alternate entire 

 leaves and usually sheathing stipules (ochrse). Flowers often 

 in racemes, occasionally diclinous. 



1. POLYGONUM. i>i?m.— Knotweed. 



(From the Greek mXvs many, and yow, a knee or joint ; the stem havmg nu- 

 merous joints.) 



Perianth mostly 5-parted, petaloid, persistent. Stamens 

 3—9, mostly 8. Styles 2—3. Fruit a one-seeded compressed 

 or triquetrous nut. 



* Mowers axillary. 



1. P. aviculare Linn.: stem mostly procumbent, herbaceous; leaves 

 elliptic-lanceolate, rough on the margin; flowers axUlary, 2—3 together; 

 nerves of the stipules distant. P. aviculare yar. procumbe7is Torr. 



Waste places. Mass. to Car. N. to Subarct. Amer. W. to the Platte River. 

 May— Sept. Q.—Stem much branched, nearly erect. Leaves v^iable m size 

 and shape. Flowers greenish-white tinged wilh purple. Knot Grass. 



2. P. eredum MuM. : stem mostly erect ; leaves broad-oval, rather obtuse, 

 petiolate, smooth ; flowers pentaiRlrous, pedicellate. P. aviculare var. lati- 

 folium Mich. var. erectum Torr. 



Near cultivated grounds. N. S. N. to Subarct. Amer. Aug. %.—Stem 1—3 

 feet high. Flowers greenish. Dr. Darlington concurs in the opmion expressed 

 by Muhlenberg, that this is a distinct species. Fl. Cest. Upright Knotweed. 



3. P. marilimum Linn. :. glaucous ; stem prostrate, with very short in- 

 ternodes ; leaves lanceolate, somewhat fleshy, often revolute on the margin ; 

 stipules half as long as the leaves, finally lacerate ; flowers axillary, 2—3 

 together, on somewhat exserted pedicels. P. glaucum Nutt. 



Sandy coast of Long Island. Torr. Aug. ® and %\—Stem mu^e and 

 Bpreadinff, woody towards the base. Flowers pale rose-color or white, twice as 

 large as in P. awcuZare. * Seaside Knotweed. 



4. P. tenue Mich. : stem slender, erect, branched, acutely angled ; leaves 

 lance-linear, erect, cuspidate ; stipules tubular, lacerate at the summit, with 

 the segments setaceously acuminate ; flowers axillary, mostly solitary, sub- 

 sessile, alternate. P. linifolium Muhl. 



Dry hills and fields. Mass. to Virg. July, Aug. OD— ^'^m 6-12 inches 

 high, scabrous on the angles. Flowers small, white, solitary and m pairs. Nut 

 acutely triangular, shining, almost black. Slender Knotweed. 



** Flowers in terminal solitary spikes. 



5. P. viviparum Linn. : stem simple ; spike linear, solitary ; leaves linear- 

 lanceolate, revolute on the margin ; the lower ones elliptic, petiolate. 



Can. White Hills, N. H., Arct. Amer. and Rocky Mountains. Aug. %.-. 

 Stem 4—8 inches high, slender. Spike ger.erally bearing httle red bulbs at the 

 lower part. Flowers pale flesh-color, almost white. _ „ , . ^^ ^ . 

 ^ BuTh-leanng Knotweed. 



