Encyclopedia of Gardening 263; 



is myrtifolia grandiflora (syn. Dalmaisiana), which produces purple 

 flowers in spring (see- the Botanical Magazine, t. 3616). It is an 

 evergreen and needs greenhouse culture. Propagation is by cut- 

 tings of the young shoots in spring under a bell-glass. Peat, with 

 sand and a third of loam, suits. 



Polygonatum, Solomon's Seal (polygona-tum, from poly, many, 

 and gonu, a joint, in reference to the stem. Ord. Liliaceae). See 

 Bulbs. 



Polygonum, Knotweed (polyg-onum, from poly, many, and gonu, 

 a joint. Ord. Polygonaceae) . A large genus which comprises some 

 very useful plants, differing widely in habit. P. affine (syn. 

 Brunonis), for example, is a dwarf hardy perennial, with rosy 

 flowers in autumn; while Baldschuanicum is a hardy perennial 

 climber, growing rapidly on trellises and arbours, and bearing a 

 cloud of white flowers in autumn ; these are two of the best. Other 

 good hardy species are alpinum, a low rock plant with white flowers 

 in summer; cuspidatum, a tall border perennial with white flowers 

 in summer; and sachalinense, a tall perennial with greenish-white 

 flowers in summer. They will grow in almost any soil, and are 

 propagated by seeds or division in spring. 



Polypodium (polypo-dium, from poly, many, and pous, foot, in 

 allusion to the divisions of the creeping stems. Ord. Filices). The 

 largest of the fern genera, mostly evergreen, but including a few 

 deciduous kinds. Loam, with sand and a third of leaf mould, suits 

 the majority. Propagation is by spores or division in spring (see 

 Ferns). The following may be selected from the hundreds of 

 species: Aureum, needs a warm greenhouse or hothouse; the name 

 comes from the yellow scales on the rootstock; several varieties, 

 Mayi being good. Dryopteris is the British Oak Fern, and is 

 deciduous; it is a prettily cut hardy species; Robertianum is a 

 scented variety of it. Phegopteris is the British Beech Fern, and 

 is partially, though not wholly, evergreen. Picotii, with broad 

 fronds, is a good greenhouse species. Schneideri is a handsome 

 hybrid, with triangular fronds, greenhouse. Subauriculatum is one 

 of the best, and makes a splendid basket fern. Vulgare is the 

 common Polypody or Wall Fern ; there are numerous varieties of it. 



Polystichum (polys-tichum, from poly, many, and stichus, a row, 

 in allusion to the spore cases. Ord. Filices). This genus of ferns 

 is now merged in Aspidium. The most popular species are acu- 

 leatum and angulare. For culture, see Ferns. 



Pondweed, Cape, Aponogeton distachyon. 



Poplar, Populus (pop-ulus, the arbor-populi or public tree of 

 the Romans. Ord. Salicineae). Useful deciduous trees, growing 

 rapidly. The Lombardy Poplar, nigra pyramidalis, is a good town 

 tree, of columnar habit. If young trees are headed at about 8 ft. 

 high they throw out thick clusters of small branches and soon make 

 a screen if planted 6 ft. apart. Alba, of which there are many varie- 

 ties, is the white Poplar or Abele. Balsamifera is the Balsam Poplar, 

 deltoidea the necklace Poplar, and tremula the Aspen (see Aspen). 

 They like well-drained loamy soil, but are not very particular. 



