153 POLYGONACEiE. Polygonum. 



»»»*»» Aticplaru, Meisn. Plowers axillary: stamens mosUyB: stigmas 3, sessile, capitate: achenium triquetrous: 

 cotyledons incumbent. — Mostly annuals : ochrea usuaUy 2 - 3-parted, or finally lacerate. 



14. Polygonum aviculare, Linn. Knot-grass. Door-weed. 



Stem procumbent or erect, geniculate, herbaceous ; leaves mostly lanceolate or elliptical ; 

 ochrese finally lacerate ; flowers axillary, nearly sessile, 2-3 together ; achenium covered 

 with the calyx, the sides ovate-triangular, rugulose-striate. — Linn. sp. I. p. 362; Engl. hot. 

 t. 1252 ; Michx. fl. 1. p. 237 ; Pursh, Jl.l. p. 269 ; Nutt. gen. 1, p. 254 ; Torr. fl. 1. 

 p. 406 ; Meisn. I. c. p. 87. 



var. 1. procumbens : stem prostrate ; leaves lanceolate-oblong. Meisn. I. c. P. aviculare. 

 Willd. sp. 2. p. 449 ; Bigel. fl. Bost.p. 155 ; Beck, hot. p. 300 ; Darlingt.fl. Cest.p. 247. 

 P. aviculare, P. angustifolium, Michx. I. c ; Pursh, I. c. ; Nutt. I. c. 



var. 2. erectum : stem erect or ascending ; leaves oval or elliptical-oblong. Meisn. I. c. P. 

 erectum, Linn. sp. 1. p. 363 ; Willd. I. c. ; Pers. syn. 1. p. 439 ; Beck, hot. p. 300 ; Nutt. 

 in Amer. phil. trans, v. (n. ser.) p. 163 ; Darlingt. I. c. P. aviculare, /3. latifolium, Michx. 

 I. c. ; Pursh, I. c. ; Nutt. I. c. ; Torr. I. c. 



Annual. Stems 6 inches to 2 feet long, strong and wiry : in var. 1. spreading flat on the 

 ground, or the branches somewhat assurgent ; in var. 2. mostly quite erect, with spreading 

 branches, somewhat thickened at the nodes, striate. Leaves in the first variety mostly 

 lanceolate, acute, half an inch to an inch long, smooth ; in the other, 1—3 inches long and 

 half an inch to an inch broad, obtuse or rather acute, bright green on both sides. Stipules 

 whitish, at length much lacerated. Flowers small, greenish white, often tinged with purple : 

 pedicels enclosed in the sheaths, or very slightly exserted. Stamens often five, included : 

 filaments dilated at the base ; three of them broader than the others, and belonging to an 

 inner series. Stigmas nearly sessile, diverging. Achenium acute, finely striate with rugulose 

 fit somewhat waved lines, rather dull. 



About houses, road-sides, gardens, etc. ; the erect variety in more damp situations : very 

 common, and probably introduced from Europe. June (var. 2. July) - November. It is 

 diflSicult to belive that the tall erect broad-leaved plant here described is a mere variety of the 

 narrow-leaved prostrate species, until one finds the intermediate forms that connect them. 

 Such states can usually be seen where the two plants grow together. 



15. Polygonum maritimum, Linn. Seaside Knot-grass. 



Stem prostrate, with very short internodes ; leaves lanceolate, glaucous (as is also the 

 stem), somewhat fleshy, often revolute on the margin ; ochreae half as long as the leaves, 

 finally lacerate ; flowers axillary, 2-3 together, the pedicels a little exserted ; achenium 

 rather longer than the calyx, smooth and shining, the sides ovate-elliptical. — Linn. sp. 1. 

 p. 361 ; Ell. sk. 1. p. 453 ; Meisn. I. c. p. 89. P. marinum, Pursh, ft. I. p. 269. P. 

 glaucum, Nutt. gen. 1. p. 254 ; Torr. fl. I. p. 401 ; Beck, hot. p. 300. 



