402 THE NURSERY-MANUAL 



Polypodium (Polypody). Polypodiacece. 



Propagation by division usually. See Ferns, page 312. 



Polyscias. Amliaceoe. 



To this genus are now referred many of the glasshouse plants 

 commonly known as aralias, others going to the genus Dizygotheca. 

 They do not seed under cultivation. Propagated by cuttings, eyes, 

 pieces of the root and grafts, usually by cuttings of firm wood. The 

 cleft or wedge methods of grafting are usually employed ; they must 

 be kept in a night temperature of not less than 70, in a tight moist 

 case. Eye-cuttings should be placed in brisk heat in a propagating- 

 bed. If the old stools are put in bottom heat, they will throw out 

 cuttings which may be removed with a heel and started in heat. 



Polystichum. Polypodiaceae. 



Propagated by spores, or by pinning down the fronds on porous 

 surface until small buds are rooted, then detached. 



Pomegranate (Punica Granatum). Punicaceoe. 



Multiplied largely by seeds, and all varieties are increased by 

 hardwood cuttings planted in open ground during February, by 

 softwood cuttings in summer, suckers, layers, and scarce kinds 

 by grafting on a common sort. 



Poncirus (commonly known as Citrus trifoliata). Rutacece. 



Propagated by seeds. See Citrus and Orange. 

 Populus (Poplar. Aspen. Cottonwood). Salicaceas. 



Raised from seeds, sown as soon as ripe and raked in, on light soil. 

 Suckers are also used. Most often increased by cuttings of ripe wood, 

 taken in fall and spring, as for willows. The weeping forms are 

 stock-grafted on upright sorts, as on P. grandidentata. 



Portulaca (Purslane. Rose Moss). Portulacacece. 



The annuals are raised from seed. Varieties are sometimes 

 propagated by cuttings. The common rose moss (P. grandiflora) is 

 grown from seed sown where the plants are to bloom. 



Potato (Solanum tuberosum). Solanaceas. 



Propagated by tubers, either whole or variously divided. From 

 8 to 20 bushels of tubers are required to plant an acre, depending on 

 how they are cut and the distance of planting. Seed grows readily 

 (when seed-balls are produced). It is sown the following spring, and 

 small tubers will result, which should be regularly planted the fol- 

 lowing year, when still larger tubers will result ; these in turn planted 



