102 POLYGONE^i: 



The great abundance of seeds furnished by this plant affords a supply to 

 a large number of our Avild singing-birds; hence its name aviailare ; and 

 insignificant as the wayside plant appears, it is of great service in the 

 economy of nature. In some counties it is called Hog-weed, because so 

 much eaten by swine. Thunberg says that, in Japan, a blue dye, resembling 

 indigo, is prepared from this j^lant ; while two exotic species of the genus 

 (P. chinense and P. harhatum) yield a good dark blue colour. 



The leaves of our little Knot-grass seem, of late years, to have been used 

 for another purpose, which may eventually render them of much importance 

 in some countries. The Liario Merrantile of Venice mentioned, in the year 

 1852, a certain Teresa Ramor, who had raised silkworms, and procured silk 

 from them in sixteen days, nourishing them with a leaf very different from 

 that of the mulberry. The writer in this journal adds : "This is the perfect 

 realization of the discovery of Anna liizzi, who could rear silkworms, even 

 in winter, giving them the leaves of the grass classed by Linmeus under the 

 name of Polygonum centinodcs." The Adriatico of Venice stated, in addition, 

 that this plant, given to these insects at the same time as the mulberry, was 

 preferred by them. The plant is said to be identical with our Knot-grass. 



4. Robert's Knot-grass (P. ro&cV/z).— Leaves distant, elliptic-lanceo- 

 late, flat ; stipules short, with few nerves ; stem prostrate ; nut smooth and 

 shining, longer than the perianth ; annual. This species is found on sandy 

 sea-shores in the west of England, Wales, and Scotland, and also about 

 Dublin. Its greenish flowers expand from July to September, and are from 

 one to three in number in the axils of the leaves. The stems are long and 

 straggling, and the leaves bend towards the stem. John Ray described this 

 plant as P. maritimum, and Mr. Babington, who names it P. rail, after that 

 gi-eat naturalist, remarks that it resembles P. mictdarc in habit, but P. mari- 

 tiinam in fruit. Its true position is considered by Sir J. D. Hooker to be as 

 a sub-species of P. aviculare. 



5. Sea-side Knot-grass (P. mariliinuni). — Flowers 1 — .3 together, 

 axillary ; leaves crowded, elliptic-lanceolate, fleshy, glaucous, with edges 

 turned under ; stipules lanceolate, with numerous branched nerves, at length 

 torn ; nut smooth and shining, longer than the perianth ; perennial. This 

 is a rare plant, found on the sands of the sea-shore in the Channel Islands, 

 and near Christchurch Head on the shore towai-ds Muddiford, also in Devon 

 and Cornwall. Its prostrate stem is described as woody below, and often 

 much buried ; its leaves are convex below, and diverging from the stem. Its 

 greenish flowers appear in August and September. 



6. Common Buckwheat (P. fagopfjrum). — Leaves arrow-shaped, 

 somewhat heart-shaped ; stem nearly upright, without prickles, branched ; 

 angles of the fruit even ; annual. The Buckwheat is a rather handsome 

 plant, with an erect, round, wavy stem, much branched, about a foot high, 

 and often of a reddish tinge. During July and August, spreading panicles 

 of pink flowers, having each eight stamens, grow at the top and sides of the 

 stem ; and the leaves, which are at first roundish in form, gradually become 

 arrow-shaped, and taper to a long point. Both stalks and leaves remain 

 green even in the driest weather, when almost all vegetation is ^\'ithered. 

 Though not truly a wild plant, yet it has long been naturalized in this 



