POLYGONACK.K. 301 



antli. Seed with farinaceous albumen and an inverted em- 

 bryo. Herbaceous plants, rarely shrubs, with alternate entire 

 leaves and usually sheathing stipules (ochrae). Flowers often 

 in racemes, occasionally diclinous. 



1. POLYGONUM. Linn. Knotweed. 



(From the Greek ToXvj many, and yow, a knee or joint ; the stem having 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. 



* Flowers axillary. 



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

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

 nerves of the stipules distant. P. aviculare var. procumbens Torr. 



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

 May Sept. (f). Stem much branched , nearly erect. Leaves variable in size 

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



2. P. erectum MM. : stem mostly erect ; leaves broad-oval, rather obtuse, 

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

 folium Mich. var. erectum Torr. 



Near cultivated grounds. N. S. N. to Subarct. Amer. Aug. 9|. Stem 1 3 

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

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



3. P. mariiimum 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. (J) and 1J-? Stem diffuse and 

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

 large as in P. aviculare. 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. (p. Stem 6 12 inches 

 high, scabrous on the angles. Flowers small, white, solitary and in 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 48 inches high, slender. Spike generally bearing little red bulbs at the 

 lower part. Flowers pale flesh-color, almost white. 



Bulb-bearing Knotweed. 



