POLYGONACEiE. 449 



Stems xisually ascending or erect, or floating. Flowers in termi- 

 nal spikes. 

 Sooistock perennial. Spikes solitary or rarely two. 



Leaves oblong-linear. Spike slender and linear 5. Viviparous P. 



Leaves ovate or oblong-lanceolate. Spike dense, oblong or 

 cylindrical. 

 Styles 3. Leaves chiefly radical. Stem-leaves few and 



small 6. Bistort F. 



Styles y. Stem floating or ascending, with large, ob- 

 long, stalked leaves 7. Amphibious F. 



Annuals. Stems branched with several spikes. 

 Spikes dense, seldom above an inch long. 

 Pedicels and perianths quite smooth. Stipules usually 



fringed 8. Fersicaria F. 



Pedicels and perianth rough with glands. Stipules usually 



entire 9. Fale F. 



Spikes long and slender ; the clusters of flowers, at least the 

 lower ones, distinct. 

 Perianth covered with raised dots. Taste biting .... 10. fVaterpepper F. 

 Perianth without raised dots. Taste not biting . . . .11. Slender P. 



Tlie tall Fersicaria of our gardens is an east Asiatic Polygonum (P. ori- 

 entale), and several other Asiatic species have been recently introduced into 

 our flower-gardens. The Buckwheat of agriculturists, occasionally found on 

 the margins of fields where it had been cultivated, is also an Asiatic plant, 

 included by some in Polygonum (P. Fagopyrwm, Eng. Bot. t. 1044), by 

 others separated into a distinct genus under the name of Fago'pyrum. 



1. Knotweed Polygonum. Polygonum aviculare, Linn. . 

 (Eng. Bot. t. 1252. Knotgrass.) 



A much branched, wiry anniial, prostrate when in the open groimd, erect 

 when drawn up amongst corn or grass, often a foot or two long. Stipules 

 white and scarious, becoming ragged at the edges. Leaves narrow-oblong, 

 small, very rarely attaimng an inch in length. Elowers small, shortly 

 stalked, in clusters of 2 to 5 in the axUs of most of the leaves. Styles 3. 

 Fruiting perianths but Httle more than a line long ; the segments white on. 

 the edge, green in the centre. Nuts triangular, seldom exceeding the peri- 

 anth, not shining, and, when seen through a strong glass, minutely granu- 

 lated or wrinkled. 



In cultivated and waste places, almost aU over the globe, from the tropics 

 to the Arctic regions. Abundant in Britain. Fl. almost the whole season. 

 It varies much in its branches, sometimes very long and slender, with very 

 few distant leaves, sometimes short and densely matted, with the small leaves 

 much crowded. A maritime variety, distinguished under the name of 

 P. Uttorale, with rather thicker leaves and larger flowers and nuts, has been 

 sometimes confounded with young or luxuriant specimens of the sea P., but 

 has not the shining nuts of that species. 



2. Sea Polygonum. Polygonum maritimum, Lian. ■ 

 (Eng. Bot. Suppl. t. 2804.) 

 When flowering the first year of its growth, or when luxtiriant, this spe- 

 cies is distinguished from the Knotioeed P. by its thicker stems, larger and 

 thicker, more glaucous leaves, larger scarious stipules, brown and much 

 veined at the base, larger flowers, and especially by the nuts, often 2 hues 

 long, projecting beyond the perianth, and very smooth and shining. Older 

 specimens, grown in drier sands, have a woody, perennial stock, with short, 

 thick branches, completely covered by the stipviles, the internodes being all 

 very short. 



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