=Pitcairnia.= See Billbergia. =Pitcher-plant.= See Nepenthes and Sarracenia. =Pittosporum.= _Pittosporeæ._ Seeds, and by cuttings of the growing or ripe wood, under glass. =Planera= (Planer-tree). _Urticaceæ._ Propagated by seeds, which should be handled like elm seeds. =Plane-tree.= See Platanus. =Plantago= (Plantain). _Plantagineæ._ Seeds. The perennial species also by division. =Plantain= (fruit). See Banana. =Platanus= (Plane-tree, Button-wood; Sycamore, improperly). _Platanaceæ._ Usually propagated by seeds, but layers and ripe wood cuttings may be employed. =Platycerium= (Stag's-Horn Fern). _Filices._ Chiefly by division. See Ferns. =Platycodon=, Wahlenbergia. _Campanulaceæ._ Propagated by seeds and, when old plants are obtainable, by division. =Plectocomia.= _Palmæ._ Seeds. May be increased by suckers. =Pleroma=, Lasiandra, including Melastoma. _Melastomaceæ._ Seeds. Propagated mostly by cuttings of growing shoots in a close frame at any season. =Plum= (_Prunus_, many species). _Rosaceæ._ There are so many species of plums in cultivation, and the varieties of the same species are often so different in constitution and habit, that it is difficult to give advice concerning their propagation. All the species grow readily from fresh, well-ripened seeds. The pits should be removed from the pulp and then stratified until spring. If they are allowed to freeze, the germination will be more uniform, as the pits will be more easily opened by the swelling embryo. Plum pits are rarely cracked by hand. The strong-growing species and varieties, especially southwards, will give stocks strong enough to bud the first season; but the weaker ones must stand until the next season after the seeds are planted. In all the northern states, however, plum pits are usually sown in seed-beds, in the same manner as apple and pear seeds. The seedlings are taken up in the fall, and the following spring set out in nursery rows, where they are budded in August.