This section is from the book "Commercial Gardening Vol2", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
A large genus of vigorous-growing plants chiefly dealt in by hardy-plant growers. The best-known member of the genus is the beautiful Japanese knotweed (P. cuspidatum or Sieboldi) which grows 6-10 ft. high, has large heart-shaped leaves and trusses of white flowers in summer. This plant flourishes in any spot and in any soil, but is generally treated as a rank weed, notwithstanding its natural beauty. The old hollow stems make excellent traps for catching earwigs on Dahlias, etc.
P. baldschuanicum, a climbing species from Turkestan, with woody stems 10 to 20 ft. long, and fleecy masses of small white flowers. The chief trade is done by nurserymen, who have propagated it in thousands during the past ten or fifteen years. Several other fine Polygonums are grown, the best being alpinum, 3 ft., white; affine (Brunonis), 6 in., rose; amplexicaule, 2-3 ft., rose red; Bistorta, 1-2 ft., rose pink; compactum, 2-4 ft, white; filiforme variegatum, 2-3 ft., the leaves of which are blotched and streaked with yellow and cream; lanigerum, 6-10 ft., deep red; multiflorum, white, tuberous rooted, climber; sachalinense, 10-12 ft., greenish white; sphoerostachyum, 3-5 ft., blood red; vaccinifolium, rose, trailer, etc.