474 FLOWERS OF GARDEN AND GREENHOUSE 



February all weak shoots must be cut right back. They require all the 

 sunshine possible. In Tropical countries Bougainvillceas occupy as 

 prominent a position on human dwellings, etc., as the Ivy and Ampelopsis 

 do with us. They are propagated by cuttings of half-ripened wood, in 

 sandy soil, on a hot-bed. 



KNOTWEEDS 



Natural Order Polygone^. Genus Polygonum 



FoLVc^oxr^t (Greek, jwlys, many, and gonu, knee ; from the many nodes). 

 A genus of about one hundred and fifty species of herbs with thickened 

 joints and alternate leaves with tubular stipules at their base sheathing 

 the stem. The flowers are small, bell-shaped or funnel-shaped, clustered 

 in panicles, racemes, or spikes. They consist of five sepals, no petals, 

 five to eight stamens, and a compressed or three-sided ovary ending in 

 three styles. The fruit is three-sided or compressed. The species are 

 widely distributed in all climates, twelve being British. 



Polygonums are not among the most desirable of garden 

 ^' plants. Our native species, with the possible exception of 

 P. Bistorta, are not worth growing, whilst some of them are perfect pests, 

 especially where manure is used or stacked, P. Bistorta, the Bistort or 

 Snakeweed, was at one time widely grown on account of its medicinal 

 reputation, and many of the plants now found in old-fashioned gardens 

 are probably the descendants of those planted there for domestic medicine. 

 In Cumberland the green-tops are — or were till recently — eaten under 

 the name of Easter Man Giants. Of those still cultivated, P. orientale 

 has been with us the longest, the first specimens having been introduced 

 from the East Indies in 1707. P. affi^ne was brought from Nepaul in 

 1822, P. cuspidatum from Japan in 1825, P. vaccinifolium from Hima- 

 laya in 1845, and P. sachalinense from the island of Sachalin in 1869. 



Polygonum affixe (related). Stems 1 foot high. 

 "Leaves stalked, lance-shaped, few. Flowers rosy, in dense 

 spikes : August to October. Hardy perennial. 



P. AMPLEXICAULE (stem-clasping). Stems 2 or 3 feet high, rising 

 from a woody rootstock. Leaves heart-shaped, the lower ones stalked. 

 Flowers rosy or white, in racemes, solitary or twin; September and 

 October. Hardy perennial. Native of Himalaya. 



P. COMPACTUM (compact). Stems 2 feet high. Leaves oval-oblong, 

 dark, slightly crimped. Flowers white, in erect racemes ; September. 



