Polygonum.] LXIII. POLYGONACE.E. 385 



from P. aviculare 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 lines long, project- 

 ing beyond the perianth, and very smooth and shining. Older speci- 

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

 thick branches, completely covered by the stipules, the internodes being 

 all very short. 



In maritime sands, on most of the seacoasts of the northern hemi- 

 sphere, and here and there also in the south. Common on the south 

 coast of England and the Channel Islands. Fl. end of summer and 

 autumn. The P. Eoberti, Loisel, or P. Fail, Bab. , is rather a young or 

 a luxuriant state of this plant than a distinct variety, although those 

 names are sometimes given to the maritime variety of P. aviculare. 



3. P. Convolvulus, Linn. (fig. 871). Black Bindweed. — A glabrous 

 annual, with a twining stem as in Convolvulus. Stipules short. Leaves 

 stalked, heart-shaped or broadly sagittate, and pointed. Flowers in 

 little loose clusters ; the lower ones axillary, the upper ones forming 

 loose, irregular terminal racemes. Styles 3. Fruiting perianth not 2 

 lines long ; the 3 outer segments closely surrounding the triangular 

 nut, and sometimes sharply keeled on the midrib, but rarely winged. 



In cultivated and waste place, throughout Europe, in central and 

 Kussian Asia, and North America, to the Arctic regions. Frequent in 

 Britain. Fl. summer and autumn. [The var. pseudo-dumetorum, Wats., 

 has broad wings on the outer sepals.] 



4. P. dunietorum, Linn. (fig. 872). Copse P. — Stem, foliage, and 

 inflorescence of P. Convolvulus, of which it may be a mere variety ; but 

 it is more luxuriant, and the 3 angles of the fruiting perianth are more 

 or less expanded into a white, scarious wing, which is often decurrent 

 on the pedicel, the whole perianth being often 3 lines long. The nut 

 is also usually more shining. 



In hedges, open woods, or rich, cultivated places, in Europe, Eussian 

 Asia, and North America, but not so common, nor extending so far 

 northward, as P. Convolvulus. In Britain, chiefly in the southern 

 counties of England. Fl. end of summer, and autumn. 



5. P. viviparum, Linn. (fig. 873). Viviparous P.— Stock perennial 

 and tuberous, with simple, erect, slender stems, 4 to 6 or rarely 8 inches 

 high. Radical leaves on long stalks, narrow-oblong or linear ; stem- 

 leaves few, nearly sessile or clasping the stem. Spike solitary and 

 terminal, slender, 1J to 3 inches long. Flowers, when perfect, pale 

 flesh-coloured, and small, with 3 styles, but the lower ones, and some- 

 times all, are converted into little red bulbs, by which the plant 

 propagates. 



In alpine pastures, often at great elevations, in all the great mountain- 

 ranges of Europe and Asia, descending to lower levels in the north, and 

 penetrating far into the Arctic regions. Frequent in the Highlands of 

 Scotland, and occurs also in northern England and North Wales, and on 

 Ben Bulben, in Ireland. M. summer. 



6. P. Bistorta, Linn. (fig. 874). Bistort, Snakeweed. — Perennial root- 

 stock thick, and often spreading considerably. Radical leaves in broad 

 patches, on long stalks, ovate-lanceolate or cordate, often 3 to 6 inches 

 long. Stems simple and erect, 1 to 2 feet high, with a few nearly sessile 

 leaves, and terminating in a single, dense, oblong, or cylindrical flower- 



2b 



